Phosphatidylinositol(4,5)bisphosphate: diverse functions at the plasma membrane

Probably not a substantial claim: may not pass S3 (load-bearing).

IP3 mobilises Ca2+ from ER stores.

“Phospholipase C (PLC) leads to the generation of two second messengers, inositol(1,4,5)trisphosphate (I(1,4,5)P3), known trigger for mobilising Ca2+ from endoplasmic reticulum (ER) stores and diacylglycerol (DAG), an activator for protein kinase C (PKC).”

• cites [7] Di Paolo, 2006, Phosphoinositides in cell regulation and membrane dynamics, Nature sourceNot checked — no full text of the source
• cites [8] Balla, 2013, Phosphoinositides: tiny lipids with giant impact on cell regulation, Physiol. Rev. sourceSupported
• cites [9] Lemmon, 2007, Pleckstrin homology (PH) domains and phosphoinositides, Biochem. Soc. Symp. sourceCould not verify

  The Background discusses Ins(1,4,5)P3 binding to PH domains, but does not say that it mobilises Ca2+ from ER stores. Searches for calcium release, ER stores, and inositol trisphosphate as a second messenger found no passage addressing that action. No page numbers are supplied in our copy. (LLM, conf=0.73)

  Experimental — accuracy not yet measured
• cites [10] Schink, 2016, Phosphoinositides in control of membrane dynamics, Annu. Rev. Cell Dev. Biol. sourceNot checked — no full text of the source
• cites [11] Duncan, 2020, Lipid-dependent regulation of ion channels and G protein-coupled receptors: insights from structures and simulations, Annu. Rev. Pharmacol. Toxicol. sourceNot checked — no full text of the source
• cites [12] Hansen, 2015, Lipid agonism: the PIP2 paradigm of ligand-gated ion channels, Biochim. Biophys. Acta sourcePartly supported

  Section 4.2 identifies IP3 as a second messenger in PLC signaling, and section 4.3 says the IP3 receptor co-localizes with PLC to regulate calcium release. The paper does not specify that this calcium is mobilized from ER stores or explicitly describe IP3 as the trigger. (LLM, conf=0.76)

  Experimental — accuracy not yet measured
• cites [13] Robinson, 2019, Tools for understanding nanoscale lipid regulation of ion channels, Trends Biochem. Sci. sourceCould not verify

  The ‘Direct versus indirect lipid regulation’ section says PIP2 generates second-messenger signals and mentions PLC, but does not identify IP3 or describe Ca2+ release from ER stores. Searches for IP3, inositol trisphosphate, and endoplasmic reticulum found no passage in our copy establishing the attributed claim; page numbers were not available. (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [14] Senju, 2019, Regulation of actin dynamics by PI(4,5)P2 in cell migration and endocytosis, Curr. Opin. Cell Biol. sourceNot checked — no full text of the source
• cites [15] Hammond, 2020, Novel roles of phosphoinositides in signaling, lipid transport, and disease, Curr. Opin. Cell Biol. sourceCould not verify

  The Introduction section on integral membrane protein signaling says that GPCRs activate PLC and deplete PI(4,5)P2, but it does not say that IP3 mobilizes Ca2+ from ER stores. Searches for IP3, inositol trisphosphate, and ER calcium release found no passage addressing that claim in our copy. (LLM, conf=0.74)

  Experimental — accuracy not yet measured
• cites [16] Dickson, 2019, Understanding phosphoinositides: rare, dynamic, and essential membrane phospholipids, Biochem. J. sourcePartly supported

  The “Physiological roles of phosphoinositides” section says PLC produces IP3 and DAG and that IP3 releases calcium from intracellular stores. It does not identify those stores specifically as the endoplasmic reticulum, so the ER-specific part of the claim is not established by our copy. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

May combine two claims.

PI(4,5)P2 is a substrate for PLC and PI3K.

“PI(4,5)P2 is a substrate for two signalling pathways.”

• cites [7] Di Paolo, 2006, Phosphoinositides in cell regulation and membrane dynamics, Nature sourceNot checked — no full text of the source
• cites [8] Balla, 2013, Phosphoinositides: tiny lipids with giant impact on cell regulation, Physiol. Rev. sourceSupported
• cites [9] Lemmon, 2007, Pleckstrin homology (PH) domains and phosphoinositides, Biochem. Soc. Symp. sourceCould not verify

  The Background describes PtdIns(4,5)P2 binding to the PH domain of PLC-δ1 and discusses PH-domain recruitment following activation of PI3K signaling. It does not state that PtdIns(4,5)P2 is a substrate for PLC or PI3K (searched for substrate, hydrolysis, and phosphorylation). (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [10] Schink, 2016, Phosphoinositides in control of membrane dynamics, Annu. Rev. Cell Dev. Biol. sourceNot checked — no full text of the source
• cites [11] Duncan, 2020, Lipid-dependent regulation of ion channels and G protein-coupled receptors: insights from structures and simulations, Annu. Rev. Pharmacol. Toxicol. sourceNot checked — no full text of the source
• cites [12] Hansen, 2015, Lipid agonism: the PIP2 paradigm of ligand-gated ion channels, Biochim. Biophys. Acta sourceSupported
• cites [13] Robinson, 2019, Tools for understanding nanoscale lipid regulation of ion channels, Trends Biochem. Sci. sourcePartly supported

  The ‘Direct versus indirect lipid regulation’ section discusses PIP2-depleting enzymes and identifies phospholipase C (PLC), supporting the PLC part of the paraphrase. Our copy does not identify PI3K or state that PIP2 is its substrate, so it does not establish the claimed two pathways. (LLM, conf=0.80)

  Experimental — accuracy not yet measured
• cites [14] Senju, 2019, Regulation of actin dynamics by PI(4,5)P2 in cell migration and endocytosis, Curr. Opin. Cell Biol. sourceNot checked — no full text of the source
• cites [15] Hammond, 2020, Novel roles of phosphoinositides in signaling, lipid transport, and disease, Curr. Opin. Cell Biol. sourcePartly supported

  The Introduction’s lipid-transfer-proteins section says PI(4,5)P2 is presented to PLCβ3 for hydrolysis, supporting the PLC part. The passages on PI3K discuss its role in disease but do not say that PI(4,5)P2 is its substrate, so the second pathway is not established by our copy. No page numbers are provided. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [16] Dickson, 2019, Understanding phosphoinositides: rare, dynamic, and essential membrane phospholipids, Biochem. J. sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing).

Mammalian PI and its derivatives predominantly have stearic acid at the sn-1 position and arachidonic acid at the sn-2 position.

“The fatty acids linked to the glycerol backbone are predominantly, stearic acid (C18:0; 18 carbons with no double bonds) at the sn-1 position and arachidonic acid (C20:4; 20 carbons with 4 double bonds) at sn-2 position [5,6] (Figure 1B).”

• cites [5] Barneda, 2019, How is the acyl chain composition of phosphoinositides created and does it matter?, Biochem. Soc. Trans. sourceSupported
• cites [6] Blunsom, 2020, Phosphatidylinositol synthesis at the endoplasmic reticulum, Biochim. Biophys. Acta Mol. Cell. Biol. Lipids sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

PI3K generates PI(3,4,5)P3, a lipid with wide-ranging functions.

“The second pathway is phosphoinositide-3-kinase (PI3K) to make PI(3,4,5)P3, a lipid with wide-ranging functions.”

• cites [7] Di Paolo, 2006, Phosphoinositides in cell regulation and membrane dynamics, Nature sourceNot checked — no full text of the source
• cites [8] Balla, 2013, Phosphoinositides: tiny lipids with giant impact on cell regulation, Physiol. Rev. sourceSupported
• cites [9] Lemmon, 2007, Pleckstrin homology (PH) domains and phosphoinositides, Biochem. Soc. Symp. sourcePartly supported

  The Background links phosphoinositide 3-kinase signaling to PH domains that recognize PtdIns(3,4,5)P3 and describes several proteins that bind the lipid. It does not explicitly state that PI3K generates PtdIns(3,4,5)P3 or establish the lipid’s wide-ranging functions. (LLM, conf=0.78)

  Experimental — accuracy not yet measured
• cites [10] Schink, 2016, Phosphoinositides in control of membrane dynamics, Annu. Rev. Cell Dev. Biol. sourceNot checked — no full text of the source
• cites [11] Duncan, 2020, Lipid-dependent regulation of ion channels and G protein-coupled receptors: insights from structures and simulations, Annu. Rev. Pharmacol. Toxicol. sourceNot checked — no full text of the source
• cites [12] Hansen, 2015, Lipid agonism: the PIP2 paradigm of ligand-gated ion channels, Biochim. Biophys. Acta sourcePartly supported

  Section 4.1 identifies PI3 kinase as the enzyme that generates PIP3 from PIP2, supporting the pathway described. The paper mentions PIP3 signaling in Section 4.5 but does not substantiate the claim that PIP3 has wide-ranging functions. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [13] Robinson, 2019, Tools for understanding nanoscale lipid regulation of ion channels, Trends Biochem. Sci. sourceCould not verify

  The sections on direct versus indirect lipid regulation and on lipids as central regulators discuss PIP2, not PI(3,4,5)P3. Searches for PI3K, PI(3,4,5)P3, and PIP3 found no passage in our copy stating that PI3K produces PI(3,4,5)P3 or describing that lipid’s functions. (LLM, conf=0.74)

  Experimental — accuracy not yet measured
• cites [14] Senju, 2019, Regulation of actin dynamics by PI(4,5)P2 in cell migration and endocytosis, Curr. Opin. Cell Biol. sourceNot checked — no full text of the source
• cites [15] Hammond, 2020, Novel roles of phosphoinositides in signaling, lipid transport, and disease, Curr. Opin. Cell Biol. sourcePartly supported

  The Introduction’s section on pathological phosphoinositide metabolism describes PI3K signaling in cancer, immunodeficiencies, growth disorders, and insulin signaling, supporting the broad point that the pathway has wide-ranging roles. However, the passages in our copy do not state that PI3K generates PI(3,4,5)P3 or specifically attribute those functions to that lipid (page unavailable). (LLM, conf=0.77)

  Experimental — accuracy not yet measured
• cites [16] Dickson, 2019, Understanding phosphoinositides: rare, dynamic, and essential membrane phospholipids, Biochem. J. sourceSupported

May combine two claims.

There are two CDS enzymes (CDS1 and CDS2) and one PIS enzyme, all localised at the ER and integral membrane proteins.

“There are two CDS enzymes, CDS1 and CDS2, and one PIS enzyme, both localised at the ER; all three enzymes are integral membrane proteins [6,22].”

• cites [6] Blunsom, 2020, Phosphatidylinositol synthesis at the endoplasmic reticulum, Biochim. Biophys. Acta Mol. Cell. Biol. Lipids sourceSupported
• cites [22] Blunsom, 2020, CDP-diacylglycerol synthases: gateway to phosphatidylinositol and cardiolipin synthesis, Front. Cell Dev. Biol. sourcePartly supported

  The ‘Mammalian CDS1 and CDS2’ section states that both CDS enzymes are integral membrane proteins and localize to ER membranes; it also places PIS at the ER in COS-7 cells. Our copy does not state that PIS is an integral membrane protein or establish that there is only one PIS enzyme, so those parts of the claim are not supported by this source. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

There are thirteen PLCs in mammals: four PLCβ, two PLCγ, three PLCδ, one PLCε, one PLCζ and two PLCη.

“Within each family are multiple members: four PLCβ (1–4), two PLCγ (1 and 2), three PLCδ (1, 3, 4), one PLCε, one PLCζ and two PLCη (1 and 2) making thirteen PLCs in total (reviewed in [27–33]) (Figure 3A).”

• cites [27] Kadamur, 2013, Mammalian phospholipase C, Annu. Rev. Physiol. sourceNot checked — no full text of the source
• cites [28] Nakamura, 2017, Regulation and physiological functions of mammalian phospholipase C, J. Biochem. sourceNot checked — no full text of the source
• cites [29] Suh, 2008, Multiple roles of phosphoinositide-specific phospholipase C isozymes, BMB Rep. sourceSupported
• cites [30] Gresset, 2012, The phospholipase C isozymes and their regulation, Subcell. Biochem. sourceSupported
• cites [31] Fukami, 2010, Phospholipase C is a key enzyme regulating intracellular calcium and modulating the phosphoinositide balance, Prog. Lipid Res. sourceNot checked — no full text of the source
• cites [32] Cocco, 2015, Phosphoinositide-specific phospholipase C in health and disease, J. Lipid Res. sourceSupported
• cites [33] Everett, 2016, The PLC pathway sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Mammalian PLC enzymes that use phosphoinositides, preferentially PI(4,5)P2, are grouped into six families (β, γ, δ, ε, ζ and η).

“In mammals, PLC enzymes that use phosphoinositides (preferentially PI(4,5)P2) as their substrates have been grouped into six families (β, γ, δ, ε, ζ and η).”

• cites [27] Kadamur, 2013, Mammalian phospholipase C, Annu. Rev. Physiol. sourceNot checked — no full text of the source
• cites [28] Nakamura, 2017, Regulation and physiological functions of mammalian phospholipase C, J. Biochem. sourceNot checked — no full text of the source
• cites [29] Suh, 2008, Multiple roles of phosphoinositide-specific phospholipase C isozymes, BMB Rep. sourceSupported
• cites [30] Gresset, 2012, The phospholipase C isozymes and their regulation, Subcell. Biochem. sourceSupported
• cites [31] Fukami, 2010, Phospholipase C is a key enzyme regulating intracellular calcium and modulating the phosphoinositide balance, Prog. Lipid Res. sourceNot checked — no full text of the source
• cites [32] Cocco, 2015, Phosphoinositide-specific phospholipase C in health and disease, J. Lipid Res. sourceSupported
• cites [33] Everett, 2016, The PLC pathway sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

DAG activates PKC.

“Phospholipase C (PLC) leads to the generation of two second messengers, inositol(1,4,5)trisphosphate (I(1,4,5)P3), known trigger for mobilising Ca2+ from endoplasmic reticulum (ER) stores and diacylglycerol (DAG), an activator for protein kinase C (PKC).”

• cites [7] Di Paolo, 2006, Phosphoinositides in cell regulation and membrane dynamics, Nature sourceNot checked — no full text of the source
• cites [8] Balla, 2013, Phosphoinositides: tiny lipids with giant impact on cell regulation, Physiol. Rev. sourceSupported
• cites [9] Lemmon, 2007, Pleckstrin homology (PH) domains and phosphoinositides, Biochem. Soc. Symp. sourceCould not verify

  The Background discusses PLCδ PH-domain binding to phosphoinositides and identifies pleckstrin as a PKC substrate, but it does not say that DAG activates PKC. Searches for DAG, diacylglycerol, and PKC activation found no passage addressing that relationship. (LLM, conf=0.73)

  Experimental — accuracy not yet measured
• cites [10] Schink, 2016, Phosphoinositides in control of membrane dynamics, Annu. Rev. Cell Dev. Biol. sourceNot checked — no full text of the source
• cites [11] Duncan, 2020, Lipid-dependent regulation of ion channels and G protein-coupled receptors: insights from structures and simulations, Annu. Rev. Pharmacol. Toxicol. sourceNot checked — no full text of the source
• cites [12] Hansen, 2015, Lipid agonism: the PIP2 paradigm of ligand-gated ion channels, Biochim. Biophys. Acta sourceCould not verify

  Section 4.4 says PLC activation generates diacylglycerol, and section 4.2 discusses downstream kinase signaling. Neither passage says that DAG activates PKC; searches for “diacylglycerol activates protein kinase C” and “PKC protein kinase C DAG” found no passage establishing that link. Page numbers were unavailable in our copy. (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [13] Robinson, 2019, Tools for understanding nanoscale lipid regulation of ion channels, Trends Biochem. Sci. sourceCould not verify

  The ‘Direct versus indirect lipid regulation’ section says PIP2 can generate second-messenger signals and that PLC co-purifies with several ion channels, but it does not say that DAG activates PKC. Searches for DAG, PKC, and protein kinase C activated by diacylglycerol found no passage addressing that relationship in our copy. (LLM, conf=0.72)

  Experimental — accuracy not yet measured
• cites [14] Senju, 2019, Regulation of actin dynamics by PI(4,5)P2 in cell migration and endocytosis, Curr. Opin. Cell Biol. sourceNot checked — no full text of the source
• cites [15] Hammond, 2020, Novel roles of phosphoinositides in signaling, lipid transport, and disease, Curr. Opin. Cell Biol. sourceCould not verify

  The Introduction section on integral membrane protein signaling says that PLC activation depletes PI(4,5)P2, but does not discuss DAG activating PKC (page unavailable). Searches for “DAG,” “PKC,” and “protein kinase C” found no passage in our copy addressing that claim. (LLM, conf=0.76)

  Experimental — accuracy not yet measured
• cites [16] Dickson, 2019, Understanding phosphoinositides: rare, dynamic, and essential membrane phospholipids, Biochem. J. sourceSupported

May combine two claims.

PI synthesis takes place in the ER, although PI phosphorylation to PI(4,5)P2 takes place at the plasma membrane.

“Although PI phosphorylation to PI(4,5)P2 takes place at the plasma membrane, the synthesis of PI takes place in the ER [6].”

• cites [6] Blunsom, 2020, Phosphatidylinositol synthesis at the endoplasmic reticulum, Biochim. Biophys. Acta Mol. Cell. Biol. Lipids sourceSupported

May combine two claims.

PI(4,5)P2 as an intact lipid regulates cytoskeletal organisation, membrane trafficking including endocytosis and exocytosis, and ion channel regulation.

“This is important as PI(4,5)P2 as an intact lipid regulates diverse cellular functions, including cytoskeletal organisation and membrane trafficking (including endocytosis and exocytosis) and ion channel regulation [10–13].”

• cites [10] Schink, 2016, Phosphoinositides in control of membrane dynamics, Annu. Rev. Cell Dev. Biol. sourceNot checked — no full text of the source
• cites [11] Duncan, 2020, Lipid-dependent regulation of ion channels and G protein-coupled receptors: insights from structures and simulations, Annu. Rev. Pharmacol. Toxicol. sourceNot checked — no full text of the source
• cites [12] Hansen, 2015, Lipid agonism: the PIP2 paradigm of ligand-gated ion channels, Biochim. Biophys. Acta sourcePartly supported

  Section 4.2 describes intact PIP2 as an ion-channel activator, supporting the ion-channel part of the claim. Section 4.4 discusses endocytosis recycling lipid microdomains after signaling, but does not say PIP2 regulates endocytosis; the passages found also do not establish cytoskeletal organisation or exocytosis as PIP2-regulated functions. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [13] Robinson, 2019, Tools for understanding nanoscale lipid regulation of ion channels, Trends Biochem. Sci. sourcePartly supported

  The ‘Challenges and opportunities’ and ‘Direct versus indirect lipid regulation’ sections describe PIP2 as a membrane lipid that regulates ion channels, including through direct binding. Our copy does not establish the claimed roles in cytoskeletal organisation or membrane trafficking, including endocytosis and exocytosis. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

PLCγ2 is highly expressed in hematopoietic cells and has a key role in signalling downstream of ITAM-associated receptors, controlling B cell and innate immune cell functions in response to BCR and FcR stimulation.

“PLCγ2, highly expressed in hematopoietic cells, has the key role in signalling downstream of ITAM-associated receptors; for example, it controls multiple functions of B cells, and several types of innate immune cells in response to stimulation of the B-cell antigen receptor (BCR) and Fc receptors (FcRs), respectively [41,42].”

• cites [41] Wang, 2000, Phospholipase Cgamma2 is essential in the functions of B cell and several Fc receptors, Immunity sourceNot checked — no full text of the source
• cites [42] Hashimoto, 2000, Cutting edge: essential role of phospholipase C-gamma 2 in B cell development and function, J. Immunol. sourcePartly supported

  The Discussion reports that PLCγ2 is a critical component of BCR signaling, and the Results show impaired B-cell responses to BCR stimulation when PLCγ2 is lost (page numbers unavailable in our copy). The cited paper does not establish the claim about high expression across hematopoietic cells, ITAM-associated receptors generally, or FcR-stimulated innate immune cell functions. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

Following phosphorylation of PLCγ1, the critical pTyr residue binds to its cSH2 domain, and this intramolecular interaction is required for repositioning of the regulatory region and release of autoinhibition.

“Following phosphorylation of PLCγ1, the critical pTyr residue in PLCγ1 binds to its cSH2 domain; this intramolecular interaction is required for repositioning of the regulatory region and release of the autoinhibition.”

• cites [47] Hajicek, 2019, Structural basis for the activation of PLC-gamma isozymes by phosphorylation and cancer-associated mutations, eLife sourcePartly supported

  The Results (Structure of full-length PLC-γ1; page not provided) describe pTyr783 as an intramolecular ligand for cSH2. The Discussion (page not provided) proposes that this engagement unlatches cSH2 and initiates regulatory-domain rearrangement, but calls that mechanism presumed rather than establishing that the interaction is required for rearrangement and release of autoinhibition. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [48] Liu, 2020, Structural insights and activating mutations in diverse pathologies define mechanisms of deregulation for phospholipase C gamma enzymes, EBioMedicine sourcePartly supported

  The Discussion (page unavailable) says that previous studies suggest phosphorylated Y783 binds the cSH2 domain, resulting in release of autoinhibition. It does not establish that this binding is required to reposition the regulatory region; instead, it says the changes that bring Y783 and cSH2 together remain unclear. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

May combine two claims.

PLCζ1 is sperm-specific and is the physiological trigger responsible for generating IP3-mediated Ca2+ oscillations that induce oocyte activation during mammalian fertilisation.

“This PLC is sperm-specific and is the physiological trigger responsible for generating I(1,4,5)P3-mediated Ca2+ oscillations that induces oocyte activation during mammalian fertilisation [43,44].”

• cites [43] Hachem, 2017, PLCzeta is the physiological trigger of the Ca(2+) oscillations that induce embryogenesis in mammals but conception can occur in its absence, Development sourcePartly supported

  The Introduction identifies PLCζ as a sperm protein, and the Results section 'Loss of PLCζ abolishes the ability of the sperm to trigger Ca2+ oscillations in the egg' calls it the physiological trigger of oscillations responsible for mammalian egg activation (page unavailable). Our copy does not establish that these oscillations are IP3-mediated; the inositol 1,4,5-trisphosphate mention found is in a reference title, not the paper’s account of this mechanism. (LLM, conf=0.87)

  Experimental — accuracy not yet measured
• cites [44] Nozawa, 2018, Sperm-borne phospholipase C zeta-1 ensures monospermic fertilization in mice, Sci. Rep. sourcePartly supported

  The Introduction identifies PLCζ1 as sperm-specific and says it can induce Ca2+ oscillations in oocytes; the Discussion identifies it as a sperm-borne oocyte activation factor in mice. But the paper also reports PLCζ1-independent Ca2+ oscillations and oocyte activation during normal fertilization, so it does not support presenting PLCζ1 as the sole physiological trigger. Its explicit account of IP3 generation describes PLC in somatic cells, rather than directly establishing that mechanism for PLCζ1 here. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

May combine two claims.

PLCβ1 has been implicated in control of neuronal function and enhancement of glucose-stimulated insulin secretion in pancreatic β-cells downstream of specific GPCRs.

“Among many roles, ubiquitously expressed PLCβ1 enzyme has been implicated in control of neuronal function and the enhancement of glucose-stimulated insulin secretion in pancreatic β-cells downstream of specific GPCRs in these different cell types [36–40].”

• cites [36] Kim, 1997, Phospholipase C isozymes selectively couple to specific neurotransmitter receptors, Nature sourceNot checked — no full text of the source
• cites [37] Biddlecome, 1996, Regulation of phospholipase C-beta1 by Gq and m1 muscarinic cholinergic receptor. Steady-state balance of receptor-mediated activation and GTPase-activating protein-promoted deactivation, J. Biol. Chem. sourcePartly supported

  The Abstract reports that an m1 muscarinic receptor activates PLCβ1 through Gq, supporting the GPCR-signaling part of the claim. Neither the Abstract nor the searched passages address control of neuronal function or enhanced glucose-stimulated insulin secretion in pancreatic β-cells; the experiments use a reconstituted protein system, not those cell types. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [38] Bohm, 2002, Disruption of PLC-beta 1-mediated signal transduction in mutant mice causes age-dependent hippocampal mossy fiber sprouting and neurodegeneration, Mol. Cell. Neurosci. sourceNot checked — no full text of the source
• cites [39] Hwang, 2019, Phospholipase C-beta1 potentiates glucose-stimulated insulin secretion, FASEB J. sourceNot checked — no full text of the source
• cites [40] Hwang, 2019, The regulation of insulin secretion via phosphoinositide-specific phospholipase Cbeta signaling, Adv. Biol. Regul. sourceNot checked — no full text of the source

May combine two claims.

PA can recruit and/or activate PIP5K and can locally influence membrane topology.

“PA can recruit and/or activate specific proteins such as PIP5K [55,56] and, with its cone-shaped geometry, PA can locally influence membrane topology and thus impact in membrane trafficking events [59].”

• cites [55] Stace, 2008, PA binding of phosphatidylinositol 4-phosphate 5-kinase, Adv. Enzyme Regul. sourceNot checked — no full text of the source
• cites [56] Cockcroft, 2009, Phosphatidic acid regulation of phosphatidylinositol 4-phosphate 5-kinases, Biochim. Biophys. Acta sourceNot checked — no full text of the source
• cites [59] Putta, 2016, Phosphatidic acid binding proteins display differential binding as a function of membrane curvature stress and chemical properties, Biochim. Biophys. Acta sourceSupported

May combine two claims.

Signalling connectivity is best defined for GPCRs and PLCβ isoforms via G-protein α and βγ subunits, and for RTKs and tyrosine kinases linked to ITAM-associated receptors that activate PLC enzymes by direct phosphorylation.

“Overall, the signalling connectivity remains best defined for the G-protein coupled receptors (GPCRs) and PLCβ isoforms, mediated by the α and βγ subunits of G-proteins, and for the RTKs and tyrosine kinases linked to immunoreceptor tyrosine-based activation motif (ITAM)-associated receptors, that activate PLC enzymes by direct phosphorylation.”

• cites [27] Kadamur, 2013, Mammalian phospholipase C, Annu. Rev. Physiol. sourceNot checked — no full text of the source
• cites [28] Nakamura, 2017, Regulation and physiological functions of mammalian phospholipase C, J. Biochem. sourceNot checked — no full text of the source
• cites [29] Suh, 2008, Multiple roles of phosphoinositide-specific phospholipase C isozymes, BMB Rep. sourceSupported
• cites [30] Gresset, 2012, The phospholipase C isozymes and their regulation, Subcell. Biochem. sourceSupported
• cites [31] Fukami, 2010, Phospholipase C is a key enzyme regulating intracellular calcium and modulating the phosphoinositide balance, Prog. Lipid Res. sourceNot checked — no full text of the source
• cites [32] Cocco, 2015, Phosphoinositide-specific phospholipase C in health and disease, J. Lipid Res. sourcePartly supported

  The Function and Regulation section (page unavailable) describes GPCR activation of PLCβ through G-protein α and βγ subunits, and RTK activation of PLCγ. It also links PLCγ activation to nonreceptor tyrosine kinases downstream of immune receptors. The passages do not identify those receptors as ITAM-associated or say that the kinases activate PLC enzymes by directly phosphorylating them; they describe binding to phosphorylated receptor residues instead. (LLM, conf=0.84)

  Experimental — accuracy not yet measured
• cites [33] Everett, 2016, The PLC pathway sourceNot checked — no full text of the source

May combine two claims.

The three classes of PI3Ks (I, II and III) differ in substrate specificity, and Class I PI3Ks selectively recognise and phosphorylate PI(4,5)P2.

“The three classes (Classes I, II and III) of these enzymes differ in their substrate specificity; the Class I PI3Ks selectively recognises and phosphorylates PI(4,5)P2 (reviewed in [60–63]).”

• cites [60] Vanhaesebroeck, 2010, The emerging mechanisms of isoform-specific PI3K signalling, Nat. Rev. Mol. Cell Biol. sourceNot checked — no full text of the source
• cites [61] Fritsch, 2013, SnapShot: class I PI3K isoform signaling, Cell sourceNot checked — no full text of the source
• cites [62] Fruman, 2017, The PI3K pathway in human disease, Cell sourcePartly supported

  In “Class I PI3K enzyme structure and activation” (page not provided), the review identifies three PI3K classes and states that class I isoforms phosphorylate PtdIns-4,5-P2. The passages do not establish how the substrate specificities of classes II and III differ, or that class I selectively recognises this substrate. (LLM, conf=0.83)

  Experimental — accuracy not yet measured
• cites [63] Burke, 2018, Structural basis for regulation of phosphoinositide kinases and their involvement in human disease, Mol. Cell sourceNot checked — no full text of the source

May combine two claims.

ERM family proteins cross-link actin filaments to the cell cortex; they have very high affinity for PI(4,5)P2 and dissociate from the membrane only under extreme circumstances.

“ERM family proteins serve to securely cross-link actin filaments to the cell cortex; they have a very high affinity for PI(4,5)P2 and only dissociates from the membrane under extreme circumstances [14,91].”

• cites [14] Senju, 2019, Regulation of actin dynamics by PI(4,5)P2 in cell migration and endocytosis, Curr. Opin. Cell Biol. sourceNot checked — no full text of the source
• cites [91] Senju, 2017, Mechanistic principles underlying regulation of the actin cytoskeleton by phosphoinositides, Proc. Natl. Acad. Sci. U.S.A. sourcePartly supported

  The Discussion identifies ezrin and moesin as cortical actin–plasma membrane linkers and reports stable, high-affinity membrane binding at low PI(4,5)P2 density. The Dynamics of ABP-Membrane Interactions section finds very slow ezrin FERM-domain dissociation, but not dissociation only under extreme circumstances; it reports about 10% fluorescence decay over 60 seconds in its assay. The binding and dissociation measurements concern FERM domains rather than establishing that behavior for every full-length ERM protein. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Oncogenic mutations in PIK3CA, encoding the p110α catalytic subunit, occur with high frequency in several common cancers.

“In particular, oncogenic mutations in the gene encoding the p110α catalytic subunit, PIK3CA, occur with high frequency in several common cancers [73].”

• cites [73] Samuels, 2010, Oncogenic mutations of PIK3CA in human cancers, Curr. Top. Microbiol. Immunol. sourceSupported

May combine two claims.

N-WASP has high affinity for PI(4,5)P2 and is activated in regions of high PI(4,5)P2 density, activating Arp2/3 to initiate actin nucleation; this is important for cell migration and N-WASP localises at extending lamellipodia.

“N-WASP has a high affinity for PI(4,5)P2, and is activated in regions with a high PI(4,5)P2 density, which in turn activates the actin-related protein 2/3 (Arp2/3) complex to initiate actin nucleation. This is important for cell migration; N-WASP localise at extending lamellipodia which are regions of high PI(4,5)P2 density.”

• cites [14] Senju, 2019, Regulation of actin dynamics by PI(4,5)P2 in cell migration and endocytosis, Curr. Opin. Cell Biol. sourceNot checked — no full text of the source
• cites [91] Senju, 2017, Mechanistic principles underlying regulation of the actin cytoskeleton by phosphoinositides, Proc. Natl. Acad. Sci. U.S.A. sourcePartly supported

  The Membranes section reports that N-WASP binding increases with PI(4,5)P2 density, and the Discussion describes relatively high-affinity binding and suggests activation in high-PI(4,5)P2 regions such as lamellipodia (page numbers unavailable). The copy does not establish the stated N-WASP-to-Arp2/3 activation sequence or show that N-WASP localizes at extending lamellipodia; its cellular-localization passage specifically describes lamellipodial accumulation of cofilin-1 and Dia2. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

PI3K activity in the p110α-p85 heterodimer is inhibited by intra- and inter-subunit contacts that become disrupted following engagement of p85 SH2 domains with phosphorylated tyrosine residues in RTK/adapter proteins, and activation favours interaction with the plasma membrane.

“In this case, the PI3K activity is inhibited by a combination of intra- and inter-subunit contacts that become disrupted following the engagement of the SH2 domains, present in p85, with the phosphorylated tyrosine residues in RTK/adapter proteins in stimulated cells; the activation also favours the interaction with the plasma membrane [74–76].”

• cites [74] Vadas, 2011, Structural basis for activation and inhibition of class I phosphoinositide 3-kinases, Sci. Signal. sourceNot checked — no full text of the source
• cites [75] Burke, 2013, Dynamic steps in receptor tyrosine kinase mediated activation of class IA phosphoinositide 3-kinases (PI3K) captured by H/D exchange (HDX-MS), Adv. Biol. Regul. sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [76] Hon, 2012, Regulation of lipid binding underlies the activation mechanism of class IA PI3-kinases, Oncogene sourcePartly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

p110γ and p110δ both play important, non-redundant roles in the immune system.

“They both play important, non-redundant roles in the immune system [68–70].”

• cites [68] Hawkins, 2015, PI3K signalling in inflammation, Biochim. Biophys. Acta sourceSupported
• cites [69] Okkenhaug, 2013, Signaling by the phosphoinositide 3-kinase family in immune cells, Annu. Rev. Immunol. sourceSupported
• cites [70] Lucas, 2016, PI3Kdelta and primary immunodeficiencies, Nat. Rev. Immunol. sourceSupported

May combine two claims.

EGF induces rapid loss of PI(4,5)P2 through PLC activity, releasing and activating a membrane-bound pool of cofilin; cofilin severs F-actin, coincident with actin polymerisation and lamellipodium formation.

“EGF induces a rapid loss of PI(4,5)P2 through PLC activity, resulting in release and activation of a membrane-bound pool of cofilin. Upon release, cofilin binds to and severs F-actin, which is coincident with actin polymerisation and lamellipodium formation [93].”

• cites [93] van, 2007, EGF-induced PIP2 hydrolysis releases and activates cofilin locally in carcinoma cells, J. Cell Biol. sourceSupported

May combine two claims.

p110α heterodimers play a key role in glucose homeostasis and in insulin and growth factor signalling.

“p110α heterodimers play a key role in glucose homeostasis and in insulin and growth factor signalling [65–67].”

• cites [65] Foukas, 2006, Critical role for the p110alpha phosphoinositide-3-OH kinase in growth and metabolic regulation, Nature sourceNot checked — no full text of the source
• cites [66] Knight, 2006, A pharmacological map of the PI3-K family defines a role for p110alpha in insulin signaling, Cell sourcePartly supported

  In “Functional Inhibition of Glucose Transport in Cells and Animals” (page unavailable), p110α inhibition blocks insulin-stimulated glucose uptake in adipocytes and the acute fall in blood glucose in mice, supporting a key role in insulin signalling and acute glucose regulation. The Discussion (page unavailable) cautions that chronic glucose homeostasis remains to be investigated. Our copy does not establish the additional claim specifically about p110α heterodimers in growth-factor signalling. (LLM, conf=0.83)

  Experimental — accuracy not yet measured
• cites [67] Hopkins, 2020, Insulin-PI3K signalling: an evolutionarily insulated metabolic driver of cancer, Nat. Rev. Endocrinol. sourceSupported

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The actin cytoskeleton provides rigidity to cells and is attached to the plasma membrane by ERM proteins.

“The actin cytoskeleton provides rigidity to the cells and is attached to the plasma membrane by Ezrin, Radixin and Moesin, collectively known as ERM proteins [89,90].”

• cites [89] Fehon, 2010, Organizing the cell cortex: the role of ERM proteins, Nat. Rev. Mol. Cell Biol. sourceSupported
• cites [90] Tsujita, 2015, Phosphoinositides in the regulation of actin cortex and cell migration, Biochim. Biophys. Acta sourceSupported

May combine two claims.

PI(4,5)P2 is one of the main drivers of actin cytoskeleton remodelling; it interacts with several actin-binding proteins at the plasma membrane and regulates their activity through its levels.

“One of the main drivers for this process is PI(4,5)P2 [87]; it interacts with several actin-binding proteins at the plasma membrane, serving to regulate their activity through its levels (Figure 5) [14,88].”

• cites [87] Raucher, 2000, Phosphatidylinositol 4,5-bisphosphate functions as a second messenger that regulates cytoskeleton-plasma membrane adhesion, Cell sourceNot checked — no full text of the source
• cites [14] Senju, 2019, Regulation of actin dynamics by PI(4,5)P2 in cell migration and endocytosis, Curr. Opin. Cell Biol. sourceNot checked — no full text of the source
• cites [88] Janmey, 2018, Regulation of actin assembly by PI(4,5)P2 and other inositol phospholipids: an update on possible mechanisms, Biochem. Biophys. Res. Commun. sourceSupported

May combine two claims.

TRPV4 channel is inhibited by PI(4,5)P2 and opens when PI(4,5)P2 levels drop, opposite to Kir2.1; depletion of PI(4,5)P2 by Gαq-PLCβ1 agonists can cause simultaneous closure of Kir2.1 and opening of TRPV4 in endothelial cells.

“The Ca2+/Na+ TRPV4 (transient receptor potential vanilloid 4) channel is inhibited by PI(4,5)P2 and opens when PI(4,5)P2 levels drop, the opposite to Kir2.1 channels. The depletion of PI(4,5)P2 by agonists such as prostaglandin E2, ATP or acetylcholine that signal through Gαq-PLCβ1 can therefore cause a simultaneous closure of Kir2.1 channels and the opening of TRPV4 channels as observed in”

• cites [117] Harraz, 2018, PIP2 depletion promotes TRPV4 channel activity in mouse brain capillary endothelial cells, eLife sourcePartly supported

  The Introduction and the Results section on GqPCR signaling state that PIP2 inhibits TRPV4 while sustaining Kir2.1 activity, and that PGE2 produces the proposed simultaneous effects in mouse brain capillary endothelial cells (pages not provided). The same Results section reports that carbachol, a muscarinic agonist, also produces both effects. But ATP inhibited Kir2.1 without affecting TRPV4, so the paper does not support including ATP among agonists that cause simultaneous Kir2.1 closure and TRPV4 opening; it also does not directly report that result for acetylcholine itself. (LLM, conf=0.91)

  Experimental — accuracy not yet measured

May combine two claims.

The GABAA receptor is a pentamer with two PI(4,5)P2 molecules constitutively associated; the PI(4,5)P2 headgroup occupies a positively charged pocket in the intracellular juxta-membrane region, and PI(4,5)P2 does not regulate channel function.

“The GABAA receptor is a pentamer and two molecules of PI(4,5)P2 are constitutively associated with the receptor. The negatively charged headgroup of PI(4,5)P2 occupies a positively charged pocket in the intracellular juxta-membrane region of one of the subunits. The function of PI(4,5)P2 is not to regulate channel function.”

• cites [13] Robinson, 2019, Tools for understanding nanoscale lipid regulation of ion channels, Trends Biochem. Sci. sourcePartly supported

  Split into 3 atoms — 0 confirmed, 3 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured
• cites [118] Laverty, 2019, Cryo-EM structure of the human α1β3γ2 GABA(A) receptor in a lipid bilayer, Nature sourcePartly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  Experimental — accuracy not yet measured

May combine two claims.

Kir2.2 channel is maintained open by PI(4,5)P2; a crystal structure shows each subunit coordinates a single PI(4,5)P2 molecule in a conserved basic pocket.

“Another example is the Kir2.2 channel, which is maintained in the open state to allow inflow of K+. A crystal structure of the inward rectifier Kir2.2 channel shows that each subunit directly coordinates a single PI(4,5)P2 molecule in a conserved basic pocket to keep the channel open [12,13].”

• cites [12] Hansen, 2015, Lipid agonism: the PIP2 paradigm of ligand-gated ion channels, Biochim. Biophys. Acta sourcePartly supported

  Section 2.3 describes a Kir2.2–PIP2 crystal structure, direct contact with basic residues, and a conformational change that appeared to open the ion pathway. Section 4.5 describes four binding sites in the tetramer, but says one PIP2 molecule is sufficient to activate the channel; it does not establish that each subunit must coordinate one PIP2 molecule to keep it open. The cited passages also do not describe the pocket as conserved. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [13] Robinson, 2019, Tools for understanding nanoscale lipid regulation of ion channels, Trends Biochem. Sci. sourcePartly supported

  The CryoEM section (page unavailable) describes an X-ray structure of PIP2 bound at a specific site in Kir2.2 and a conformational change consistent with lipid gating. It does not say that each subunit coordinates exactly one PIP2 molecule in a conserved basic pocket, or establish that PIP2 maintains the channel in an open state. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

May combine two claims.

After clathrin recruitment, PI(4,5)P2 facilitates membrane deformation; epsin binds PI(4,5)P2 and inserts an amphipathic helix, and BAR domain proteins also contribute.

“After clathrin recruitment, PI(4,5)P2 facilitates membrane deformation. Epsin binds to PI(4,5)P2, localising epsin to the endocytic site where it inserts an amphipathic helix for membrane deformation [101,102]. Accessory proteins with BAR (domain named after three proteins: Bin, Amphiphysin and Rvs that share the domain) domains, which also bind PI(4,5)P2, also contribute to deformation of the”

• cites [101] Garcia-Alai, 2018, Epsin and Sla2 form assemblies through phospholipid interfaces, Nat. Commun. sourceSupported
• cites [102] Ford, 2002, Curvature of clathrin-coated pits driven by epsin, Nature sourceNot checked — no full text of the source
• cites [103] Yoon, 2012, Phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) specifically induces membrane penetration and deformation by Bin/amphiphysin/Rvs (BAR) domains, J. Biol. Chem. sourcePartly supported

  The Discussion (page unavailable) says that epsin1’s ENTH helix forms a PI(4,5)P2-binding site, and the paper describes that helix as penetrating the membrane. Figure 7 and the Discussion support PI(4,5)P2-dependent membrane deformation by N-BAR domains. Our copy does not establish the claimed sequence after clathrin recruitment or specifically show that PI(4,5)P2 localises epsin to the endocytic site. (LLM, conf=0.82)

  Experimental — accuracy not yet measured

May combine two claims.

AP2 activates PIP 5-kinase for increased PI(4,5)P2 production, promoting further AP2 recruitment and assembly of endocytic vesicles.

“A positive feedback loop is also established as AP2 activates PIP 5-kinase for increased PI(4,5)P2 production, promoting further recruitment of AP2 and assembly of endocytic vesicles [100].”

• cites [100] Krauss, 2006, Stimulation of phosphatidylinositol kinase type I-mediated phosphatidylinositol (4,5)-bisphosphate synthesis by AP-2mu-cargo complexes, Proc. Natl. Acad. Sci. U.S.A. sourcePartly supported

  The Results report that AP-2μ–cargo complexes activate PI(4,5)P2-synthesizing PIPK, and the Discussion links PI(4,5)P2 to AP-2 membrane association and endocytic coated-pit formation. But the Discussion says this mechanism could provide a positive feedback loop; it does not establish that the loop drives endocytic vesicle assembly as the citing sentence states. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

PI(4,5)P2 is dephosphorylated by 5-phosphatases for uncoating to take place; excess PI(4,5)P2 inhibits endocytosis by preventing uncoating and subsequent vesicular fusion.

“PI(4,5)P2 is dephosphorylated by 5-phosphatases for uncoating to take place [104]. Thus, although PI(4,5)P2 facilitates the mechanism of clathrin vesicle endocytosis, excess PI(4,5)P2 inhibits endocytosis. Persistence of PI(4,5)P2 on vesicular membranes prevents the uncoating of the vesicle and subsequent vesicular fusion with the target membrane [105].”

• cites [104] Wallroth, 2018, Phosphoinositide conversion in endocytosis and the endolysosomal system, J. Biol. Chem. sourcePartly supported

  The section on PI(4,5)P2 conversion during coated-pit maturation says that 5-phosphatases hydrolyze PI(4,5)P2 and that loss of these enzymes impairs endocytosis and causes clathrin-coated vesicles to accumulate. It does not explicitly establish that dephosphorylation is required for uncoating, or that persistent PI(4,5)P2 prevents subsequent fusion with a target membrane. The latter statement has a separate citation [105] in the citing text. (LLM, conf=0.82)

  Experimental — accuracy not yet measured
• cites [105] Kim, 2002, Delayed reentry of recycling vesicles into the fusion-competent synaptic vesicle pool in synaptojanin 1 knockout mice, Proc. Natl. Acad. Sci. U.S.A sourcePartly supported

  The Discussion (page unavailable) proposes that persistently high PI(4,5)P2 may delay vesicle uncoating and reports impaired reentry into the functional synaptic-vesicle pool. It does not show that uncoating is prevented or that fusion with a target membrane is blocked; the Results say coated vesicles eventually uncoat. The dephosphorylation statement is attached to citation [104], not this source’s citation [105]. (LLM, conf=0.88)

  Experimental — accuracy not yet measured

May combine two claims.

Plasma membrane lipids are not homogeneously distributed but segregated; lipid rafts are platforms enriched in cholesterol and sphingolipids where signalling proteins can accumulate.

“Our understanding of the plasma membrane has evolved with the recognition that the lipids are not homogeneously distributed but are segregated; one early concept was ‘lipid rafts’ as platforms enriched in cholesterol and sphingolipids, in which specific proteins involved in signalling can accumulate [122,123].”

• cites [122] Sezgin, 2017, The mystery of membrane organization: composition, regulation and roles of lipid rafts, Nat. Rev. Mol. Cell Biol. sourceSupported
• cites [123] Levental, 2020, Lipid rafts come of age, Nat. Rev. Mol. Cell. Biol. sourceNot checked — no full text of the source

May combine two claims.

PI(4,5)P2 forms dynamic clusters at nanoscale; STED microscopy on PC12 cell plasma membranes found clusters of ∼65-73 nm.

“Using super-resolution stimulated-emission depletion (STED) microscopy on the plasma membranes of PC12 cells, PI(4,5)P2 was found in clusters of ∼65–73 nm in size [110,126].”

• cites [110] van den Bogaart, 2011, Membrane protein sequestering by ionic protein-lipid interactions, Nature sourceSupported
• cites [126] Wang, 2012, Segregation of PIP2 and PIP3 into distinct nanoscale regions within the plasma membrane, Biol. Open sourcePartly supported

  The Results and Discussion (Fig. 1 and accompanying text) report PIP2 clusters of about 64–65 nm in PC12 cell plasma membranes, but this paper used dSTORM, not STED microscopy. The same section cites a separate STED study for the approximately 73 nm figure. The cited sentence does not attribute cluster dynamics to this source. (LLM, conf=0.90)

  Experimental — accuracy not yet measured

May combine two claims.

PI(4,5)P2 recruits dynamin to the plasma membrane where it assembles at the neck of the budding vesicle and mediates fusion of the non-cytosolic leaflets.

“PI(4,5)P2 also plays a crucial role in the recruitment of dynamin to the plasma membrane where it assembles at the neck of the budding vesicle and mediates fusion of the non-cytosolic leaflets of the membrane [99].”

• cites [99] Mettlen, 2018, Regulation of Clathrin-Mediated Endocytosis, Annu. Rev. Biochem. sourcePartly supported

  The 'Dynamin: A Key Regulator of CME' section says dynamin assembles around the neck of deeply invaginated clathrin-coated pits and catalyzes membrane fission. 'Regulating CCP Growth and Maturation' links PI(4,5)P2 to a neck-localized SNX9 pathway, but does not establish that PI(4,5)P2 directly recruits dynamin. The passages do not describe dynamin mediating fusion of the non-cytosolic leaflets. Page numbers were not available in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured

Probably not a substantial claim: may not pass S3 (load-bearing).

Aberrant functions of different PLCs and PI3Ks in disease development are well established.

“Although not covered in this review, the importance of aberrant functions of different PLCs and PI3Ks in disease development is well established and continues to expand [11,62,67,72,134–138].”

• cites [11] Duncan, 2020, Lipid-dependent regulation of ion channels and G protein-coupled receptors: insights from structures and simulations, Annu. Rev. Pharmacol. Toxicol. sourceNot checked — no full text of the source
• cites [62] Fruman, 2017, The PI3K pathway in human disease, Cell sourcePartly supported

  The Introduction and Historical Context states that aberrations in PI3K signaling contribute to a broad spectrum of human diseases. It does not establish the corresponding claim about PLCs, so this source supports only the PI3K part of the citing sentence. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [67] Hopkins, 2020, Insulin-PI3K signalling: an evolutionarily insulated metabolic driver of cancer, Nat. Rev. Endocrinol. sourcePartly supported

  The section “Regulation of cellular growth and metabolism” (page unavailable) links altered PI3K activity and mutations in PI3K components to cancers, overgrowth syndromes, and SHORT syndrome. The passages retrieved do not address aberrant PLC function, so the source supports the PI3K part of the claim but not the PLC part. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [72] Goncalves, 2018, Phosphatidylinositol 3-kinase, growth disorders, and cancer, N. Engl. J. Med. sourceNot checked — no full text of the source
• cites [134] Magno, 2019, Alzheimer's disease phospholipase C-gamma-2 (PLCG2) protective variant is a functional hypermorph, Alzheimers Res. Ther. sourcePartly supported

  The Background links mutations in two PLCs, PLCγ1 and PLCγ2, to cancers, neuropsychiatric disorders, and inherited immune disorders. The paper does not make a corresponding claim about aberrant PI3K function; PI3K appears only in a reference title among the passages found. No page numbers were provided in our copy. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites [135] Zhou, 2012, A hypermorphic missense mutation in PLCG2, encoding phospholipase Cγ2, causes a dominantly inherited autoinflammatory disease with immunodeficiency, Am. J. Hum. Genet. sourceNot checked — no full text of the source
• cites [136] Ombrello, 2012, Cold Urticaria, immunodeficiency, and autoimmunity related to PLCG2 deletions, N. Engl. J. Med. sourceSupported
• cites [137] Koss, 2014, Dysfunction of phospholipase Cgamma in immune disorders and cancer, Trends Biochem. Sci. sourcePartly supported

  The section “Mutations in PLCγ enzymes and disease development” (p. 3) links aberrant PLCγ function to immune disorders and cancer, supporting the PLC portion of the claim. The paper does not substantiate the claim about PI3Ks in disease development; its focus is PLCγ enzymes. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites [138] Neves, 2018, Novel PLCG2 mutation in a patient with APLAID and Cutis Laxa, Front. Immunol. sourcePartly supported

  The Case Report links a gain-of-function PLCγ2 mutation to disease in one patient, supporting the claim for that PLC. The Introduction distinguishes PLC isoforms, but the paper does not establish disease roles for different PLCs or for PI3Ks; the broader claim is not supported by this source alone. Page numbers are unavailable in our copy. (LLM, conf=0.87)

  Experimental — accuracy not yet measured

May combine two claims.

PI(4,5)P2 functions in two distinct roles: as a substrate for PLC and PI3K, and as a primary messenger.

“As a result, the functions of PI(4,5)P2 can be explored in two separate and distinct roles – as a substrate for phospholipase C (PLC) and phosphoinositide 3-kinase (PI3K) and as a primary messenger, each having unique properties.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

PI(4,5)P2 is the most abundant phosphoinositide and is enriched in the cytoplasmic leaflet of the plasma membrane, comprising 1-2 mol% of total plasma membrane lipid.

“Of these, PI(4,5)P2 is the most abundant phosphoinositide and is enriched in the cytoplasmic leaflet of the plasma membrane comprising 1–2 mol% of total plasma membrane lipid [3,4].”

• cites [3] McLaughlin, 2005, Plasma membrane phosphoinositide organization by protein electrostatics, Nature sourceNot checked — no full text of the source
• cites [4] McLaughlin, 2002, PIP(2) and proteins: interactions, organization, and information flow, Annu. Rev. Biophys. Biomol. Struct. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

PI(4,5)P2 is a low-abundance cellular membrane phospholipid generated by phosphorylation of PI.

“Phosphatidylinositol(4,5)bisphosphate (PI(4,5)P2), is a low abundance, cellular membrane phospholipid generated by phosphorylation of phosphatidylinositol (PI) (Figure 1A).”

May combine two claims.

Following PLC activation, DAG is rapidly converted into PA and utilised for the synthesis of PI.

“Following PLC activation, DAG is rapidly converted into PA and is utilised for the synthesis of PI (Figure 2).”

May combine two claims.

PA can be obtained by de novo synthesis or from the PI(4,5)P2-PLC cycle.

“PA can be either obtained by de novo synthesis, or from the PI(4,5)P2-PLC cycle.”

Probably not a substantial claim: may not pass S3 (load-bearing).

PLCs hydrolyse glycerophospholipids, including phosphoinositides, at the phosphodiester bond.

“PLCs hydrolyse different glycerophospholipids, including phosphoinositides, at the phosphodiester bond (between the glycerol backbone and the phosphate group).”

May combine two claims.

PI(4,5)P2 is highly negatively charged and can bind unstructured clusters of basic residues on membrane proteins such as ion channels, receptors and cytoskeletal proteins.

“In addition, PI(4,5)P2 is a highly negatively charged lipid and therefore can bind unstructured clusters of basic residues on numerous membrane proteins (for example, ion channels, receptors and cytoskeletal proteins) [3,11] (see Figure 1C).”

• cites [3] McLaughlin, 2005, Plasma membrane phosphoinositide organization by protein electrostatics, Nature sourceNot checked — no full text of the source
• cites [11] Duncan, 2020, Lipid-dependent regulation of ion channels and G protein-coupled receptors: insights from structures and simulations, Annu. Rev. Pharmacol. Toxicol. sourceNot checked — no full text of the source

May combine two claims.

PI synthesis is a two-step process: PA is converted to CDP-DAG by CDS enzymes, then to PI by PIS.

“PI synthesis is a two-step process, the conversion of PA (phosphatidic acid) into the intermediate, cytidine diphosphate DAG (CDP-DAG) by CDP-DAG synthase (CDS) enzymes followed by its conversion into PI by PI synthase (PIS) (Figure 2).”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Conversion of PI4P into PI(4,5)P2 is catalysed by PI4P 5-kinases, and three isoforms (PI4P5Kα, β, γ) have been identified in mammals.

“The conversion of PI4P into PI(4,5)P2 is catalysed by PI4P 5-kinases and three isoforms (PI4P5Kα, β, γ) have been identified in mammals.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

It is more likely that PA generated during the PI(4,5)P2-PLC cycle is segregated for resynthesis into PI.

“However, it is more likely that the PA, generated during the PI(4,5)P2 – PLC cycle, is segregated for resynthesis into PI.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

Mammals express four Class I PI3K catalytic subunits (p110α, p110β, p110γ and p110δ) and five regulatory subunits (p85α, p85β, p55α, p50α and p55γ).

“Mammals express four catalytic subunits (p110α, p110β, p110γ and p110δ) and five regulatory subunits (p85α, p85β, p55α, p50α and p55γ).”

Probably not a substantial claim: may not pass S3 (load-bearing).

Six PLC families share a conserved core structure in addition to a variety of other domains specific for each family.

“As outlined in Figure 3A, six PLC families share a conserved core structure in addition to a variety of other domains specific for each family.”

Probably not a substantial claim: may not pass S3 (load-bearing).

IP3 binds IP3 receptors at the ER to release Ca2+ into the cytosol from ER stores.

“I(1,4,5)P3 binds to IP3 receptors present at the ER to release Ca2+ into the cytosol from the ER stores whilst hydrophobic DAG binds to C1 domains (protein kinase C conserved region 1) of proteins for membrane recruitment and activation.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

In PLCβ, the unique C-terminal domain has been implicated in interactions with Gαq and with the membrane.

“In PLCβ, the unique C-terminal domain has been implicated in interactions with Gαq and with the membrane.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

PLCε contains a CDC25 domain with Ras GEF activity and two Ras association (RA) domains.

“PLCε contains a CDC25 domain (cell division cycle 25 (Ras GEF domain) has Ras GEF (guanine nucleotide exchange factor) activity) and two Ras association (RA) domains, both related to the regulatory interplay with small GTPases.”

Probably not a substantial claim: may not pass S3 (load-bearing).

A seventh PLC family, PLC-XD, has been discovered across different eukaryotic species, including three isoforms in humans.

“Recently, a seventh family of PLCs was discovered across different eukaryotic species, including three isoforms in humans, and named PLC-XD (PLC X-domain containing protein) [34]; more research is, however, needed to fully understand distinct properties and biological functions of PLC-XD enzymes.”

• cites [34] Gellatly, 2012, Cloning, tissue distribution and sub-cellular localisation of phospholipase C X-domain containing protein (PLCXD) isoforms, Biochem. Biophys. Res. Commun. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Both products of PLC hydrolysis, IP3 and DAG, are second messengers.

“It is well established that both products of PLC hydrolysis, I(1,4,5)P3 and DAG, are second messengers.”

May combine two claims.

PI(4,5)P2 concentrations regulate processes by affecting recruitment of peripheral membrane proteins and by regulation of integral membrane proteins.

“As already outlined in the introduction, PI(4,5)P2 concentrations regulate a number of processes by affecting recruitment of peripheral membrane proteins and by regulation of integral membrane proteins.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The γSA contains a split PH domain (sPH), two Src homology 2 domains (nSH2 and cSH2) and a Src homology 3 (SH3) domain.

“The γSA contains a ‘split’ PH domain (sPH), two Src homology 2 domains (nSH2 and cSH2) and a Src homology 3 (SH3) domain.”

Probably not a substantial claim: may not pass S3 (load-bearing).

In PLCγ isoforms, the linker between the two halves of the catalytic TIM-barrel is known as the γ-specific array (γSA).

“In PLCγ isoforms, the linker between the two halves of the catalytic TIM-barrel differs from a relatively short, disordered region in all other families and is known as the γ-specific array (γSA) (coloured pink in Figure 3A).”

May combine two claims.

IP3 is a substrate for the synthesis of inositol polyphosphates including IP7 and IP8, which are recognised as signalling molecules.

“I(1,4,5)P3 is also a substrate for the synthesis of inositol polyphosphates including pyro-phosphates such as IP7 and IP8 which are recognised as signalling molecules, including metabolic messengers or energy sensors [50].”

• cites [50] Wilson, 2013, Inositol pyrophosphates: between signalling and metabolism, Biochem. J. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

In PLCδ1, the PH domain binds PI(4,5)P2, whereas in PLCβ isoforms the PH domain interacts with Rac.

“for example, the PH domain (pleckstrin homology domain) in PLCδ1 binds PI(4,5)P2 while in PLCβ isoforms, it interacts with a small GTPase Rac.”

Probably not a substantial claim: may not pass S3 (load-bearing).

PLC-XD enzymes are more related to bacterial PLCs whose substrate is PI rather than PI(4,5)P2.

“The PLC-XD enzymes are more related to bacterial PLCs whose substrate is PI rather than PI(4,5)P2 [35].”

• cites [35] Roberts, 2018, Search and subvert: minimalist bacterial phosphatidylinositol-specific phospholipase C enzymes, Chem. Rev. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

Class I PI3Ks are heterodimers of a p110 catalytic subunit with a regulatory subunit that keeps the heterodimer in an inactive, cytosolic state.

“These PI3Ks are heterodimers of a p110 catalytic subunit (that includes the kinase domain) with a regulatory subunit that keeps the heterodimer in an inactive, cytosolic state.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Class I PI3Ks act in signalling downstream of plasma membrane-bound receptors and small GTPases.

“The Class I enzymes act in signalling downstream of plasma membrane-bound receptors and the small GTPases.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The PI3K pathway is one of the most frequently dysregulated in cancer, and PI3Ks are studied as targets for cancer therapy.

“In addition to their diverse functions established in normal cells, PI3Ks are also quite extensively studied as targets for cancer therapy; the PI3K pathway is one of the most frequently dysregulated in cancer [71,72].”

• cites [71] Janku, 2018, Targeting the PI3K pathway in cancer: are we making headway?, Nat. Rev. Clin. Oncol. sourceNot checked — no full text of the source
• cites [72] Goncalves, 2018, Phosphatidylinositol 3-kinase, growth disorders, and cancer, N. Engl. J. Med. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Class IA PI3Ks (p110α, p110β and p110δ) bind p85/p50/p55-type regulatory subunits, while Class IB (p110γ) binds p101 or p87.

“A Class IA (p110α, p110β, and p110δ) binds the p85/p50/p55 type of regulatory subunits while Class IB (p110γ) binds one of two related regulatory subunits, p101 and p87, which have no homology to other proteins or recognisable domain structure (Figure 4A).”

May combine two claims.

FOXO transcription factors' involvement in PI3K signalling is less clear and most likely substantially cell-context dependent.

“In contrast, the involvement of the FOXO transcription factors in PI3K signalling is less clear and most likely, substantially cell-context dependent”

May combine two claims.

Talin contains a FERM domain that attaches to PI(4,5)P2 and binds PIP5Kγ, defining a mechanism for spatial generation of PI(4,5)P2 at focal adhesions.

“Talin contains a FERM domain that allows the protein to attach to PI(4,5)P2. Talin also binds to PIP5Kγ, the enzyme that makes PI(4,5)P2, defining a mechanism for spatial generation of PI(4,5)P2 at focal adhesions [96–98].”

• cites [96] Barsukov, 2003, Phosphatidylinositol phosphate kinase type 1gamma and beta1-integrin cytoplasmic domain bind to the same region in the talin FERM domain, J. Biol. Chem. sourceNot checked — no full text of the source
• cites [97] Di Paolo, 2002, Recruitment and regulation of phosphatidylinositol phosphate kinase type 1 gamma by the FERM domain of talin, Nature sourceNot checked — no full text of the source
• cites [98] Ling, 2002, Type I gamma phosphatidylinositol phosphate kinase targets and regulates focal adhesions, Nature sourceNot checked — no full text of the source

May combine two claims.

Cofilin has low affinity for PI(4,5)P2 and is retained at the plasma membrane under resting conditions when PI(4,5)P2 levels are high; when PI(4,5)P2 levels fall, cofilin is released into the cytosol to promote actin filament disassembly.

“Proteins such as cofilin that disassemble actin filaments have low affinity for PI(4,5)P2. Thus cofilin is retained at the plasma membrane under resting conditions when PI(4,5)P2 levels are high. During actin cytoskeletal remodelling, when PI(4,5)P2 levels are locally altered, proteins that aid actin filament disassembly such as cofilin are released into the cytosol where it can engage in disas”

• cites [14] Senju, 2019, Regulation of actin dynamics by PI(4,5)P2 in cell migration and endocytosis, Curr. Opin. Cell Biol. sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing).

p110α and p110β have a broad tissue distribution.

“p110α and p110β have a broad tissue distribution.”

May combine two claims.

p110γ and p110δ are highly expressed in immune cells but are also found in some other tissues at lower levels.

“p110γ and p110δ are highly expressed in the immune cells but are also found in some other tissues at lower levels.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

All p110 catalytic subunits can interact with members of the Ras GTPase superfamily.

“Additionally, all p110 catalytic subunits can interact with members of Ras GTPase superfamily.”

May combine two claims.

ERM proteins contain a FERM domain that directly binds PI(4,5)P2, and this interaction releases the autoinhibited state of the protein.

“ERM proteins contain the FERM domain that directly binds to PI(4,5)P2. This interaction is important for releasing the autoinhibited state of the protein.”

May combine two claims.

Actin-binding proteins have differing affinities for PI(4,5)P2, so PI(4,5)P2 level at the plasma membrane can tightly regulate actin cytoskeleton dynamics, with decreased PI(4,5)P2 decreasing actin stability.

“In general, actin binding proteins have differing affinities for PI(4,5)P2, meaning that the level of PI(4,5)P2 at the plasma membrane can tightly regulate the dynamics of the actin cytoskeleton, with decreased PI(4,5)P2 levels having the overall effect of decreased actin stability.”

May combine two claims.

PI(4,5)P2 binds and regulates a range of proteins, a subset of which regulates the actin cytoskeleton.

“PI(4,5)P2 similarly binds and regulates a range of proteins; a subset of these downstream effectors is involved in regulation of actin cytoskeleton.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Activation of p110α and p110δ is mediated by binding of their heterodimers to pYXXM motifs, p110γ through binding of βγ subunits, and p110β can be activated via both types of interactions.

“As a generalised overview, activation of the lipid kinase present in p110α and p110δ is mediated by binding of their heterodimers to the pYXXM motifs, in p110γ through the binding of βγ subunits while p110β can be activated via both types of interactions.”

May combine two claims.

KCNQ channels are maintained in the open state by PI(4,5)P2; M1 receptor activation via Gαq/PLCβ1 causes a robust decrease in PI(4,5)P2 and channel closure; IP3 and DAG do not directly contribute; PI(4,5)P2 resynthesis reopens the channels.

“The best characterised example is the KCNQ channels which are maintained in the open state allowing K+ to move freely (Figure 6B). Upon stimulation with the muscarinic agonist, M1 receptors are activated which couple to Gαq and activate PLCβ1. A robust decrease in PI(4,5)P2 causes channel closure; the PI(4,5)P2 hydrolysis products IP3 and DAG do not contribute directly to channel regulation. Res”

• cites [115] Delmas, 2005, Pathways modulating neural KCNQ/M (Kv7) potassium channels, Nat. Rev. Neurosci. sourceNot checked — no full text of the source
• cites [116] Zhang, 2003, PIP(2) activates KCNQ channels, and its hydrolysis underlies receptor-mediated inhibition of M currents, Neuron sourceNot checked — no full text of the source

May combine two claims.

PLC activation depletes PI(4,5)P2, leading to inactivation of PI(4,5)P2-dependent channels.

“A variety of signalling pathways involve PLC activation and so PI(4,5)P2 depletion, leading to the inactivation of these PI(4,5)P2-dependent channels.”

May combine two claims.

AP2 exists in a closed conformation in the cytosol with clathrin and PI(4,5)P2/cargo binding sites buried; interaction with plasma membrane PI(4,5)P2 triggers an allosteric change to an open conformation exposing these sites, allowing clathrin recruitment.

“AP2 exists in a closed conformation in the cytosol, in which the clathrin binding site is buried by interactions between the β2 hinge and the core. The PI(4,5)P2 and cargo binding sites on the μ2 subunit are also buried in this conformation. The interaction of surface-exposed binding sites on both the α- and β2-adaptin with plasma membrane-enriched PI(4,5)P2 triggers an allosteric conformational”

May combine two claims.

PI(4,5)P2 has an important role both as a substrate for PLC and PI3K and as a regulatory ligand for peripheral and integral membrane proteins.

“Among different phosphoinositides, PI(4,5)P2 has an important role both, as a substrate for two types of key signalling enzymes (PLC and PI3K) and as a regulatory ligand for peripheral and integral membrane proteins.”

May combine two claims.

Stabilisation of GPCRs in the active state increases GTPase activity and enhances selectivity of coupling to G proteins.

“Stabilisation of the receptors in the active state increases GTPase activity and enhances selectivity of coupling to G proteins.”

May combine two claims.

There is strong evidence for PI(4,5)P2 segregation, but many caveats remain due to technical limitations.

“Although there is strong evidence to support segregation of PI(4,5)P2, as discussed above, there remains many caveats due to technical limitations [132,133].”

• cites [132] Hammond, 2016, Does PtdIns(4,5)P2 concentrate so it can multi-task?, Biochem. Soc. Trans. sourceNot checked — no full text of the source
• cites [133] Omar-Hmeadi, 2018, PtdIns(4,5)P(2) is not required for secretory granule docking, Traffic sourceNot checked — no full text of the source

May combine two claims.

Local enrichment of PI(4,5)P2 can occur by preferential trapping in lipid rafts, binding proteins such as MARCKS, syntaxin-1 and K-Ras, or localised recruitment of PIP5K.

“Local enrichment of PI(4,5)P2 can occur by multiple mechanisms [131,132]. There can be preferential trapping of PI(4,5)P2 in lipid rafts, binding proteins such as MARCKS (myristoylated alanine-rich C-kinase substrate), syntaxin-1 and K-Ras that sequester PI(4,5)P2, or localised recruitment of PIP5K to generate PI(4,5)P2.”

• cites [131] Hilgemann, 2007, Local PIP2 signals: when, where, and how?, Pflüg. Arch. sourceNot checked — no full text of the source
• cites [132] Hammond, 2016, Does PtdIns(4,5)P2 concentrate so it can multi-task?, Biochem. Soc. Trans. sourceNot checked — no full text of the source

May combine two claims.

PI(4,5)P2 diffusion at the cytoplasmic leaflet of cellular plasma membranes is much lower than in protein-free membranes, and two thirds of PI(4,5)P2 is reversibly bound to proteins.

“The diffusion coefficient is much lower and results indicate that two thirds of the PI(4,5)P2 is reversibly bound to proteins.”

• cites [124] Golebiewska, 2008, Diffusion coefficient of fluorescent phosphatidylinositol 4,5-bisphosphate in the plasma membrane of cells, Mol. Biol. Cell sourceNot checked — no full text of the source

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Tools available for specifically imaging PI(4,5)P2, including the PH domain of PLCδ, have limitations and further development is required.

“Some tools are available for specifically imaging PI(4,5)P2 (including the widely-used PH domain of PLCδ) but these have limitations and therefore further development is required.”