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Cited by 459Cellular transport and secretionLysosomal Storage Disorders ResearchAutophagy in Disease and Therapy

The DOI matches its Crossref record; 48 of the 48 references it cites were found in a registry or an index; 11 of the 20 sources its claims cite were checked for support.

The sortilin cytoplasmic tail conveys Golgi–endosome transport and binds the VHS domain of the GGA2 sorting protein

Open access
Nielsen, Morten S., Madsen, Peder, Christensen, Erik I., Nykjær, Anders, Gliemann, Jørgen, Kasper, Dagmar, Pohlmann, Regina, Petersen, Claus M.·2001·The EMBO Journal
DOI 10.1093/emboj/20.9.2180PMC PMC125444
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Abstract

Sortilin belongs to a growing family of multiligand type-1 receptors with homology to the yeast receptor Vps10p. Based on structural features and sortilin's intracellular predominance, we have proposed it to be a sorting receptor for ligands in the synthetic pathway as well as on the cell membrane. To test this hypothesis we examine here the cellular trafficking of chimeric receptors containing constructs of the sortilin tail. We report that sorting signals conforming to YXX and dileucine motifs mediate rapid endocytosis of sortilin chimeras, which subsequently travel to the trans-Golgi network, showing little or no recycling. Furthermore, we found that cation-independent mannose 6-phosphate receptor (MPR300)-sortilin chimeras, expressed in mannose 6-phosphate receptor knockout cells, were almost as efficient as MPR300 itself for transport of newly synthesized beta-hexosaminidase and beta-glucuronidase to lysosomes, and established that the sortilin tail contains potent signals for Golgi-endosome sorting. Finally, we provide evidence suggesting that sortilin is the first example of a mammalian receptor targeted by the recently described GGA family of cytosolic sorting proteins, which condition the Vps10p-mediated sorting of yeast carboxypeptidase Y.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

The sortilin cytoplasmic tail contains endocytic and Golgi–endosome sorting signals that direct chimeric receptors to the trans-Golgi network and can substitute for the MPR300 tail in lysosomal enzyme transport. Sortilin binds the GGA2 sorting protein via its VHS domain, and this interaction requires the C-terminal dileucine motif.

Key findings

  • Endocytosis of IL2R–sortilin chimeras depends mainly on the YXXF motif Y14SVL17 and, to a lesser extent, the C-terminal dileucine L51L52. At 30 min, non-internalized tracer was 41.5 ± 6.3% for wild-type tail, 76.5 ± 4.5% for Y14A/L17A, and 90.5 ± 1.2% for Y14A/L17A plus deletion of L51L52; combined disruption accounted for ~80% reduction in endocytosis.
  • Internalized IL2R–sortilin-wt traveled through clathrin-coated vesicles and Lamp-1-negative early endosomes to the TGN, co-localizing with TGN38 at 60 min, with little or no recycling over 4 h.
  • MPR300–sortilin-wt chimeras in mannose 6-phosphate receptor-deficient (mpr−) cells corrected secretion of newly synthesized β-hexosaminidase and β-glucuronidase and normalized lysosome morphology. At optimal expression, medium from transfected cultures contained ~80% less β-hexosaminidase than untransfected cells; with mannose 6-phosphate, <40% of the enzyme was found in the medium.
  • Sortilin binds GGA2 via the GGA2 VHS domain; >10% of the labeled sortilin pool was precipitated by GST–GGA2s, and deletion of the C-terminal dileucine abolished the interaction in two-hybrid and pull-down assays.

Methods

  • Chimeric receptors were generated by combining the sortilin cytoplasmic domain (wild-type or mutated/deleted at candidate motifs) with the luminal and transmembrane domains of IL2Rα (CD25/Tac) or MPR300. IL2R–sort chimeras were expressed in CHO-K1 cells; MPR300–sort chimeras were expressed in mouse embryonic fibroblasts deficient in both mannose 6-phosphate receptors (mpr−).
  • Endocytosis was measured with 125I-labeled anti-Tac/anti-CD25 and acid wash (pH 2.5); trafficking was analyzed by confocal and electron microscopy, surface biotinylation/metabolic labeling, and β-hexosaminidase fluorometric assays in the absence or presence of mannose 6-phosphate.
  • Protein interactions were tested by yeast two-hybrid screening with sortilin cytoplasmic domain as bait and by GST pull-down assays using GGA2 constructs, including the VHS domain and GAEH domain.

Limitations

  • The paper states that evidence for PACS-1 involvement and for the acidic cluster in sortilin trafficking was inconclusive; cell-to-cell variation was not insignificant and further evidence was needed. Full-length GGA2 could not be purified as a uniform protein.
  • Evident from the text: conclusions rely on chimeric receptors and antibody–receptor complexes, which may not fully reflect full-length sortilin behavior; several assays used transfected cells with varying expression levels and clone-to-clone differences.
  • No in vivo validation is reported.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1093/emboj/20.9.2180

Cites

48 of 48 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

11 of 20 cited sources checked · 5 supported · 0 flagged · accuracy not yet measured

  • Interpretationcitation
    § Motifs for sortilin internalization

    Previous evidence on sortilin and MPR300 co-localization supports full-length sortilin as a functional sorting receptor.

    “This is in good agreement with previous evidence on sortilin and MPR300 co-localization, and in strong support of full-length sortilin as a functional sorting receptor (Petersen et al., 1997;Morris et al., 1998).”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites Petersen et al., 1997 source

      The section headed “Transient Expression of gp95/Sortilin and Chimeric Receptors” (page not provided) reports co-localization with the CI-M6P receptor for a chimera bearing sortilin’s cytoplasmic tail, not for full-length sortilin. The paper describes sortilin as a candidate sorting receptor; it does not establish that the full-length protein functions as one. (LLM, conf=0.87)

      Experimental — accuracy not yet measured
    • cites Morris et al., 1998 source

      The Abstract (page unavailable) reports that sortilin appears to colocalize with CIM6PR (MPR300) in COS cells and says this suggests a sorting-receptor role. The Discussion (page unavailable) says sortilin’s function remains undetermined and that it could instead be a receptor for an extracellular ligand. The source therefore supports the prior colocalization and the proposed role, but not an established function for full-length sortilin as a sorting receptor. (LLM, conf=0.86)

      Experimental — accuracy not yet measured
  • Premisecitation
    § Motifs for sortilin internalization

    Vps10p-mediated sorting of CPY is impaired in gga null cells.

    “Thus, Vps10p-mediated sorting of CPY is impaired in gga null cells (Hirst et al., 2000)”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Hirst et al., 2000 source
  • Findingown data
    § Endocytosis of chimeric receptors

    During a 4 h chase at 37°C, little or no internalized 125I-labelled anti-Tac returned to the surface in a pH 2.5-releasable form.

    “Accordingly, during a 4 h chase at 37°C, little or no internalized 125 I-labelled anti-Tac returned to the surface in a pH 2.5-releasable form.”
    Quote in the paperSubstantial claim
  • Findingown data
    § Sortilin`s cytoplasmic tail conveys Golgi±endosome transport

    Chimeras carrying Y14A as a single mutation showed no signs of missorting.

    “However, it should be noted that chimeras carrying Y 14 A as a single mutation showed no signs of missorting.”
    Quote in the paperSubstantial claim
  • Findingown data
    § Motifs for sortilin internalization

    L51A/L52A had little impact on cellular uptake.

    “since L 51 A/L 52 A had little impact on the cellular uptake, in agreement with ®ndings in CHO cells”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim. 11
  • It may state two separate claims as one. 30
  • The quote only partly states this claim. 1

  • Probably not a substantial claim. It may state two separate claims as one.

    Premisecitation
    § Motifs for sortilin internalization

    Sorting of CPY is clathrin independent (restores in the absence of functional clathrin heavy chains).

    “Since sorting of CPY is clathrin independent, i.e. restores in the absence of functional clathrin heavy chains (Seeger and Payne, 1992)”
    Quote in the paperSubstantial claim1 of 1 sources checked
    • cites Seeger and Payne, 1992 source

      The Discussion (page unavailable) says CPY delivery can occur without functional clathrin heavy chain, and the Results report improved sorting after 3 hours at 37°C. But the paper also reports a rapid, severe sorting defect when clathrin function is first impaired. Calling CPY sorting simply clathrin independent omits that qualification. (LLM, conf=0.88)

      Experimental — accuracy not yet measured

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation
    § Motifs for sortilin internalization

    GGA2 belongs to a recently described family of monomeric cytosolic proteins that includes three mammalian and two yeast members.

    “GGA2 belongs to a recently described family of monomeric cytosolic proteins that includes three mammalian and two (gga) yeast members (Boman et al., 2000;Dell'Angelica et al., 2000;Hirst et al., 2000;Poussu et al., 2000;Takatsu et al., 2000).”
    Quote in the paperNot a substantial claim2 of 3 sources checked
    • cites Boman et al., 2000 source
    • cites Dell'Angelica et al., 2000 source

      The Results sections identify GGA2 as one of three human GGAs, alongside two yeast counterparts, and report that most endogenous GGA2 was in a cytosolic fraction. However, the biochemical characterization says its sedimentation is compatible with either a monomer or an asymmetrically shaped dimer; it does not establish that GGA2 is monomeric. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites Hirst et al., 2000 source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation
    § Motifs for sortilin internalization

    Important findings in yeast convincingly implicate the GGA family in Golgi-endosome/lysosome transport.

    “Information concerning their physiological function is still limited, but important ®ndings in yeast convincingly implicate the family in Golgi±endosome/lysosome transport.”
    Quote in the paperNot a substantial claim2 of 2 sources checked
    • cites Hirst et al., 2000 source
    • cites Black and Pelham, 2000 source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation
    § Motifs for sortilin internalization

    Incorporation of the syntaxin Pep12p in late endosomes is dependent on gga proteins.

    “and the incorporation of the syntaxin Pep12p in late endosomes is likewise dependent on gga proteins (Black and Pelham, 2000).”
    Quote in the paperNot a substantial claim1 of 1 sources checked
    • cites Black and Pelham, 2000 source

  • It may state two separate claims as one.

    Premisecitation
    § Introduction

    Sortilin predominates in intracellular compartments, with only a minor fraction on the cell surface and about 90% in Golgi and vesicles co-localizing with MPR300.

    “Only a minor fraction of the receptors is expressed on the cell surface, whereas ~90% are found in Golgi and vesicles, showing extensive co-localization with MPR300 (Petersen et al., 1997;Morris et al., 1998).”
    Quote in the paperSubstantial claim2 of 2 sources checked
    • cites Petersen et al., 1997 source

      In “Transient Expression of gp95/Sortilin and Chimeric Receptors” (page unavailable), full-length sortilin localized particularly to the Golgi, with no detectable cell-surface staining. A receptor bearing sortilin’s tail co-localized with the cation-independent mannose-6-phosphate receptor in the Golgi and endosome-like vesicles. The paper does not report that approximately 90% of sortilin is in those compartments, and the co-localization experiment used a chimeric receptor rather than full-length sortilin. (LLM, conf=0.88)

      Experimental — accuracy not yet measured
    • cites Morris et al., 1998 source

      The Abstract says sortilin is largely located in intracellular GLUT4-containing vesicles in adipocytes and reports apparent co-localization with the cation-independent mannose 6-phosphate receptor in COS cells. The results on vesicle isolation report 70–75% of sortilin in the sampled fraction in GLUT4 vesicles, not that ~90% of all sortilin is in Golgi and vesicles; the paper also does not quantify the fraction at the cell surface. Pages are not specified in our copy. (LLM, conf=0.87)

      Experimental — accuracy not yet measured

  • It may state two separate claims as one.

    Findingown data
    § Sortilin binds the cytosolic sorting protein GGA2

    Neither full-length sortilin nor the chimeric receptor was precipitated upon incubation with the C-terminal GAEH construct.

    “The results demonstrate that neither fulllength sortilin nor the chimeric receptor was precipitated upon incubation with the C-terminal GAEH construct (Figure 8C and D).”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Sortilin binds the cytosolic sorting protein GGA2

    Both full-length GGA2 and GGA2s induced a positive response with sortilin-cd as bait.

    “In control experiments, both full-length GGA2 and GGA2s induced a positive response with sortilin-cd as bait (data not shown).”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data
    § Endocytosis of chimeric receptors

    Internalized IL2R-sort-wt chimeras are directed to the TGN without recycling.

    “Internalized IL2R±sort-wt chimeras are directed to the TGN without recycling”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Endocytosis of chimeric receptors

    Y14SVL17 is the main signal for endocytosis, responsible for about 60% of the activity, and the tyrosine is the single most important residue.

    “The time course of [ 125 I]anti-Tac internalization by IL2R±sort chimeras is delineated in Figure 2 and clearly designates Y 14 SVL 17 as the main signal for endocytosis, being responsible for ~60% of the activity, and the tyrosine as the single most important residue.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Motifs for sortilin internalization

    Neither the acidic cluster H44-D50 nor the S41GY43 motif constitutes an active signal in sortilin.

    “Neither the acidic cluster (H 44 ±D 50 ) nor S 41 GY 43 (a signal in Lamp-1 and -2) appears to constitute active signals in sortilin.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Sortilin binds the cytosolic sorting protein GGA2

    GST-VHS mediated precipitation of a considerable fraction of IL2R-sort-wt but produced little or no pull-down of IL2R-sort-del L51L52.

    “In accordance, GST±VHS mediated precipitation of a considerable fraction of the IL2R±sort-wt contained in CHO lysates but produced little or no pull-down of the IL2R±sort-del L 51 L 52 (Figure 9B).”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Sortilin binds the cytosolic sorting protein GGA2

    GGA2s contains the first 193 N-terminal residues of the published GGA2 sequence, including the entire VHS domain, followed by the amino acid sequence LFLSASEPGPIHFPSTMNSPNRYSLDISI.

    “The translated product of the isolated clone (GGA2s) therefore represents a truncated form of GGA2, which contains the ®rst 193 N-terminal residues of the published GGA2 sequence, including the entire VHS domain, followed by the amino acid sequence LFLSASEPGPIHFPSTMNSPNRYSLDISI.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Motifs for sortilin internalization

    Internalized receptors travel to the TGN seemingly by a route bypassing Lamp-1-positive endosomes and show little or no recycling.

    “Following internalization in coated pits, chimeric receptors (and full-length sortilin) travel to the TGN seemingly by a route bypassing Lamp-1-positive (late) endosomes.Internalized receptors, at least when complexed with antibodies, show little or no recycling.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Motifs for sortilin internalization

    The sortilin cytoplasmic domain conveys endocytosis and TGN localization as well as transport from the synthetic pathway to lysosomes.

    “we have demonstrated that the sortilin cytoplasmic domain conveys endocytosis and TGN localization as well as transport from the synthetic pathway to lysosomes”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Sortilin binds the cytosolic sorting protein GGA2

    Constructs not containing the C-terminal dileucine failed to induce a response in yeast, suggesting that disruption of this motif abolished proper binding of GGA2.

    “The results (Figure 9A) demonstrate that constructs not containing the C-terminal dileucine failed to induce a response in yeast cells (blue staining), suggesting that disruption of this motif abolished proper binding of GGA2.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Sortilin binds the cytosolic sorting protein GGA2

    A two-hybrid screen using sortilin-cd as bait identified a differentially spliced version of human GGA2 cDNA (GGA2s).

    “Among the resulting con®rmed positive clones, which did not include any adaptor protein (m) subunits, one was found to be a differentially spliced version of human GGA2 cDNA (DDBJ/EMBL/GenBank accession No. AF323754).”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Sortilin binds the cytosolic sorting protein GGA2

    The GGA2s construct mediated pull-down of both sortilin and IL2R-sort-wt.

    “In contrast, the splice variant GGA2s construct mediated pull-down, in intra-(data not shown) as well as extracellular buffer, of both sortilin and IL2R±sort-wt (e.g. Figure 8C)”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Sortilin`s cytoplasmic tail conveys Golgi±endosome transport

    While beta-glucuronidase was released into the medium in its proform, the cells contained only the converted mature enzyme, indicating that retained enzyme had been directed to lysosomes.

    “SDS±PAGE analysis (Figure 6, left panel inset) demonstrates that while b-glucuronidase was released into the medium in its proform, the cells contained only the converted mature enzyme, providing evidence that retained (not secreted) enzyme had been directed to the lysosomes.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The MPR300-sort chimeras bind the mannose 6-phosphate moieties of proenzymes via the MPR300 luminal domain.

  • It may state two separate claims as one.

    Findingown data
    § Endocytosis of chimeric receptors

    IL2R-sort-wt internalizes a maximum of about 67% of bound anti-Tac within 2 h, similar to the about 75% of labelled antisortilin internalized by CHO cells expressing full-length sortilin.

    “Using this method, a maximum of ~67% of the total amount of anti-Tac bound by IL2R±sort-wt was internalized within 2 h, which is similar to the amount (~75%) of labelled antisortilin internalized by CHO cells expressing full-length sortilin (data not shown).”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Findingown data
    § Endocytosis of chimeric receptors

    Chimeras with impaired endocytic function accumulated on the cell surface; the fraction of mutant receptors exposed on the plasma membrane was 1.3-, 2.8- and 3.8-fold higher than IL2R-sort-wt for L51L52 deleted, Y14A/L17A, and the two combined, respectively.

    “Using this approach, we found that the fraction of mutant receptors exposed on the plasma membrane was 1.3-(L 51 L 52 deleted), 2.8-(Y 14 A/L 17 A) and 3.8-(the two combined) fold higher than that of IL2R±sort-wt.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Findingown data
    § Motifs for sortilin internalization

    Only L17A, and not Y14A, had a clear impact on intracellular transport.

    “but, surprisingly, only L 17 A and not Y 14 A had a clear impact on intracellular transport.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one. The quote only partly states this claim.

    Findingown data
    § Endocytosis of chimeric receptors

    At 60 min, anti-Tac-receptor complexes largely co-localized with TGN38, with scarce co-localization with Lamp-1.

    “At 60 min, staining predominated in vesiculotubular structures in close proximity to the nucleus, and double staining demonstrated that the antibody±receptor complexes to a large extent co-localized with TGN38 (Figure 4, panel 3).”
    • Also stated in: § Endocytosis of chimeric receptors · plain
      “It is remarkable that co-localization with Lamp-1 was scarce and only seen upon prolonged incubation (>45 min).”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Interpretationreasoning
    § Sortilin`s cytoplasmic tail conveys Golgi±endosome transport

    In terms of sorting from the synthetic pathway, L17 may be a key residue, but tyrosine and the YXXF motif as such are not functionally significant.

    “It follows that in terms of sorting from the synthetic pathway, L 17 may be a key residue, but tyrosine and the YXXF motif as such are not functionally signi®cant.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Interpretationreasoning
    § Sortilin`s cytoplasmic tail conveys Golgi±endosome transport

    The dileucine almost only contributes to direct intracellular transport, whereas residues of the YXXF motif promote transport by endocytosis as well as by sorting from the Golgi.

    “From ®ndings obtained in the absence and presence of mannose 6-phosphate, it can further be deduced that the dileucine almost only contributes to the direct intracellular transport, whereas residues of the YXXF motif promote transport by endocytosis as well as by sorting from the Golgi”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. It may state two separate claims as one.

    Premisecitation
    § Sortilin`s cytoplasmic tail conveys Golgi±endosome transport

    mpr− cells are unable to transfer newly synthesized lysosomal enzymes from the secretory pathway to late endosomes, release the ligands into the medium and have abnormal lysosomes.

    “Owing to their receptor de®ciency, these (mpr ± ) cells are unable to transfer newly synthesized lysosomal enzymes, normally targeted by the mannose 6-phosphate receptors, from the secretory pathway to the late endosomes.The cells consequently release the ligands into the medium and are left with abnormal lysosomes.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites Pohlmann et al., 1995 source

  • It may state two separate claims as one.

    Interpretationown data
    § Sortilin`s cytoplasmic tail conveys Golgi±endosome transport

    Sortilin-cd has the capacity for Golgi-endosome sorting, and this function relies on sorting motifs other than those governing endocytosis.

    “The ®ndings establish that sortilin-cd has the capacity for Golgi±endosome sorting and the evidence is that this function relies on sorting motifs other than those governing endocytosis.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim.

    Study design and conductnone given
    § Immunocytochemistry

    False positives were identified and eliminated by co-transforming EGY48[p8op-lacZ] cells with the rescued library plasmids as well as bait plasmids without insert or with a non-interacting insert.

    “False positives were identi®ed and eliminated by co-transforming EGY48[p8op-lacZ] cells with the rescued library plasmids as well as bait plasmids without insert or with a non-interacting insert.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Interpretationown data
    § Motifs for sortilin internalization

    The sortilin-cd can substitute for the MPR300-cd and provide direct transport to lysosomes for ligands bound in the synthetic pathway as well as on the plasma membrane.

    “Thus, unlike the cytoplasmic domains of other transmembrane proteins residing in the TGN, e.g.TGN38 and furin (D.Kasper and R.Pohlmann, unpublished results), the sortilin-cd can substitute for the MPR300-cd and provide direct transport to lysosomes for ligands bound in the synthetic pathway as well as on the plasma membrane.”
    Quote in the paperSubstantial claim
    • Rests on an assumption: The MPR300-sort chimeras bind the mannose 6-phosphate moieties of proenzymes via the MPR300 luminal domain.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation
    § Motifs for sortilin internalization

    Both types of motif mediate binding to AP complexes involved in budding of TGN transport vesicles (AP-1 and -3) as well as endocytosis (AP-2).

    “In any case, both types of motif mediate binding to AP complexes involved in budding of TGN transport vesicles (AP-1 and -3) as well as endocytosis (AP-2) (reviewed in Bonifacino and Dell'Angelica, 1999;Kirchhausen, 1999).”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites Bonifacino and Dell'Angelica, 1999 source

      Checked before — its earlier verdict is held back until a new check runs.

    • cites Kirchhausen, 1999 source

  • It may state two separate claims as one.

    Interpretationown data
    § Endocytosis of chimeric receptors

    Sortilin-cd mediates endocytosis of IL2R-sort-wt in clathrin-coated vesicles, avoids recycling and directs the receptors to the TGN via Lamp-1-negative endosomes.

    “It can be concluded from the above that sortilin-cd mediates endocytosis of IL2R±sort-wt in clathrin-coated vesicles, avoids recycling and directs the receptors to the TGN via Lamp-1-negative endosomes.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Study design and conductnone given
    § Immunocytochemistry

    Blue colonies were subcloned three times to eliminate noninteracting plasmids.

    “Blue colonies were subcloned three times to eliminate noninteracting plasmids.”
    Quote in the paperNot a substantial claim

  • It may state two separate claims as one.

    Interpretationown data
    § Motifs for sortilin internalization

    Alternative transporter molecules may target the sortilin tail, as demonstrated by the two-hybrid screen and pull-down experiments involving sortilin and GGA2.

    “However, as demonstrated by the two-hybrid screen and pull-down experiments involving sortilin and GGA2, alternative transporter molecules may target the sortilin tail.”
    Quote in the paperSubstantial claim

  • It may state two separate claims as one.

    Interpretationown data
    § Discussion

    The sortilin cytoplasmic domain conveys Golgi localization and Golgi-endosome transport.

    “demonstrates that in addition to endocytosis the sortilin cytoplasmic domain conveys Golgi localization and Golgi±endosome transport.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Premisecitation
    § Abstract

    Sortilin belongs to a family of multiligand type-1 receptors with homology to the yeast receptor Vps10p.

    “Sortilin belongs to a growing family of multiligand type-1 receptors with homology to the yeast receptor Vps10p.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Marcusson et al., 1994 source

  • Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

    Premisecitation
    § Motifs for sortilin internalization

    GGAs are ARF dependent and Golgi localizing, and comprise, from the N-terminus, a VHS domain, a GAT domain, a linker region and a C-terminal GAEH domain.

    “GGAs are ARF dependent and Golgi localizing, and comprise, from the N-terminus, a VHS domain, a so-called GAT domain, a linker region and a C-terminal GAEH domain (Dell'Angelica et al., 2000).”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites Dell'Angelica et al., 2000 source

      Checked before — its earlier verdict is held back until a new check runs.

  • Probably not a substantial claim. The paper’s conclusions may not depend on it.

    Study design and conductown data
    § DNA constructs

    The correct composition of the above constructs was ensured by sequencing.

    “The correct composition of the above constructs was ensured by sequencing in a Licore 4200 or the ABI 373A system (MWG, Germany).”
    Quote in the paperNot a substantial claim
36 of 36

  • The paper relies on this without support.

    Mannose 6-phosphate inhibits ligand binding at the cell surface and prevents uptake from the medium.

    “Since mannose 6-phosphate inhibits ligand binding at the cell surface and thereby prevents uptake from the medium, it follows that the chimeric receptor, similarly to MPR300 itself, downregulates the cellular secretion of b-hexosaminidase.”

  • The paper relies on this without support.

    The MPR300-sort chimeras bind the mannose 6-phosphate moieties of proenzymes via the MPR300 luminal domain.

    “Since these chimeras (MPR300±sort) bind the mannose 6-phosphate moieties of proenzymes via the MPR300 luminal domain, we were then able to determine their sorting by monitoring the fate and cellular release of ligands, i.e. b-hexosaminidase.”

  • The paper relies on this without support.

    Sortilin is similar to the CPY sorting receptor Vps10p.

    “in view of the similarity between sortilin and the CPY sorting receptor Vps10p”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Sortilin is a lysosomal sorting protein that binds ligands both in the Golgi apparatus and at the plasma membrane and traffics them to the lysosome.

    “Sortilin is a lysosomal sorting protein that binds ligands both in the Golgi apparatus and at the plasma membrane and traffics them to the lysosome.”

    From Hepatic sortilin regulates both apolipoprotein B secretion and LDL catabolism (2012) · cites this paper as [6]

    The Introduction describes sortilin as a candidate sorting receptor for ligands in the synthetic pathway and at the cell surface. The ‘Motifs for sortilin internalization’ section reports transport to lysosomes from both routes, but the experiment used a chimera with sortilin’s tail and another receptor’s ligand-binding domain. It supports a sorting role for full-length sortilin without directly showing that native sortilin binds ligands in both locations and carries them to lysosomes. Page numbers are unavailable in our copy. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • Sortilin localizes primarily to the Golgi apparatus.

    “Sortilin localizes primarily to the Golgi apparatus”

    From Hepatic sortilin regulates both apolipoprotein B secretion and LDL catabolism (2012) · cites this paper as [6]

    The Introduction reports that sortilin predominates in intracellular compartments, with about 90% found in the Golgi and vesicles. The Discussion says its cytoplasmic domain conveys Golgi localization, but the copy does not establish that the Golgi apparatus alone is sortilin’s primary location. (LLM, conf=0.82)

    Experimental — accuracy not yet measured

  • Sort.Stop was predominantly either secreted or in an intracellular, nonlysosomal location, while Sort.LAYA localized disproportionately to the plasma membrane.

    “Sort.Stop was predominantly either secreted or in an intracellular, nonlysosomal location, while Sort.LAYA localized disproportionately to the plasma membrane (Supplemental Figure 4, A-D), consistent with previous observations (6).”

    From Hepatic sortilin regulates both apolipoprotein B secretion and LDL catabolism (2012) · cites this paper as [6]

    In “Endocytosis of chimeric receptors” (page not available), the paper reports that a sortilin-tail mutant with a disrupted YXXF motif had 2.8-fold more receptor exposed on the plasma membrane than the wild-type chimera, consistent with the Sort.LAYA observation. Our copy does not identify Sort.Stop or establish that it was predominantly secreted or in an intracellular, nonlysosomal location; the secretion results concern lysosomal enzymes, not Sort.Stop. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

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Metadata

Authors
Nielsen, M. S., Madsen, P., Christensen, E. I., Nykjær, A., Gliemann, J., Kasper, D., Pohlmann, R., & Petersen, C. M.
Affiliations
  • Aarhus University (DK)
  • Universität Hamburg (DE)
  • University of Münster (DE)
Corresponding author
  • Nielsen, Morten S.
  • Petersen, Claus M.
ORCID
Venue
The EMBO Journal
Publisher
Springer Science and Business Media LLC
Published
2001-05-01
Volume
20
Issue
9
Pages
2180-2190
ISSN
  • 0261-4189 (ISSN-L)
  • 1460-2075
DOI
10.1093/emboj/20.9.2180
PMC
PMC125444
OpenAlex
W1997957892
Semantic Scholar
c8a98d3e68ff0ec3bb6a392554900f8f02118f76
Cited by
457
References
46
Citations by year
2026: 14 · 2025: 10 · 2024: 8 · 2023: 18 · 2022: 11 · 2021: 12 · 2020: 15 · 2019: 23 · 2018: 14 · 2017: 20 · 2016: 24 · 2015: 18 · 2014: 17 · 2013: 16 · 2012: 18
FWCI
6.89
Type
journal article
Language
en
Open access
Licence
Locations
  • The EMBO Journal (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • Aarhus Universitet
  • Aarhus Universitets Forskningsfond
  • Novo Nordisk Fonden
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Cellular transport and secretion
  • Health Sciences › Medicine › Genetics (clinical) › Lysosomal Storage Disorders Research
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Autophagy in Disease and Therapy
Keywords
sortilin, cytoplasmic tail, GGA2, VHS domain, endocytosis, YXXΦ motif, dileucine motif, trans-Golgi network, lysosomal sorting, mannose 6-phosphate receptor, beta-hexosaminidase, beta-glucuronidase, chimeric receptors, carboxypeptidase Y
MeSH terms
Sortilin, Amino Acid Sequence, Animals, Carrier Proteins, Cytoplasm, Endocytosis, Fungal Proteins, Golgi Apparatus, Cricetinae, Humans, Membrane Glycoproteins, Nerve Tissue Proteins, Protein Binding, Proteins, Receptors, Cell Surface, Endosomes, Recombinant Fusion Proteins, Transfection, Receptors, Interleukin-2, Gene Expression, CHO Cells, Protein Structure, Tertiary, Two-Hybrid System Techniques, Amino Acid Motifs, Protein Transport, Saccharomyces cerevisiae Proteins, Vesicular Transport Proteins, Adaptor Proteins, Vesicular Transport

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

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