Differential requirements for AP-2 in clathrin-mediated endocytosis
Open accessAbstract
AP-2 complexes are key components in clathrin-mediated endocytosis (CME). They trigger clathrin assembly, interact directly with cargo molecules, and recruit a number of endocytic accessory factors. Adaptor-associated kinase (AAK1), an AP-2 binding partner, modulates AP-2 function by phosphorylating its μ2 subunit. Here, we examined the effects of adenoviral-mediated overexpression of WT AAK1, kinase-dead, and truncation mutants in HeLa cells, and show that AAK1 also regulates AP-2 function in vivo. WT AAK1 overexpression selectively blocks transferrin (Tfn) receptor and LRP endocytosis. Inhibition was kinase independent, but required the full-length AAK1 as truncation mutants were not inhibitory. Although changes in μ2 phosphorylation were not detected, AAK1 overexpression significantly decreased the phosphorylation of large adaptin subunits and the normally punctate AP-2 distribution was dispersed, suggesting that AAK1 overexpression inhibited Tfn endocytosis by functionally sequestering AP-2. Surprisingly, clathrin distribution and EGF uptake were unaffected by AAK1 overexpression. Thus, AP-2 may not be stoichiometrically required for coat assembly, and may have a more cargo-selective function in CME than previously thought.
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CME requires the AP2 complex to recruit cargo proteins to endocytic vesicles.
“To recruit cargo proteins to endocytic vesicles, CME requires the heterotetrameric adaptor protein complex AP2 complex that acts as an adaptor between cargo proteins and clathrin coats (5, 15–18).”
From Regulation of cargo exocytosis by a Reps1-Ralbp1-RalA module (2023) · cites this paper as [16]
The Introduction describes AP-2 as a heterotetramer that facilitates coupling clathrin to cargo. But the Results and discussion conclude that AP-2 has a cargo-selective requirement in CME and that other adaptors can package cargo independently of it. The claim overstates AP-2 as universally required for cargo recruitment. (LLM, conf=0.88)
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Self-citation
- Authors
- Conner, S. D., & Schmid, S. L.
- Affiliations
- Scripps Research Institute (US)
- Venue
- The Journal of Cell Biology
- Publisher
- Rockefeller University Press
- Published
- 2003-09-01
- Volume
- 162
- Issue
- 5
- Pages
- 773-780
- ISSN
- 0021-9525 (ISSN-L)
- 1540-8140
- PMC
- PMC2172816
- OpenAlex
- W2100278600
- Cited by
- 196
- References
- 0
- Citations by year
- 2026: 5 · 2025: 7 · 2024: 5 · 2023: 10 · 2022: 1 · 2021: 13 · 2020: 10 · 2019: 8 · 2018: 3 · 2017: 8 · 2016: 7 · 2015: 1 · 2014: 3 · 2013: 6 · 2012: 8
- FWCI
- 5.66
- Type
- journal article
- Language
- en
- Open access
- green
- www.ncbi.nlm.nih.gov
- Licence
- cc-by-nc-sa
- Locations
- The Journal of Cell Biology (publishedVersion)
- PubMed Central (publishedVersion, cc-by-nc-sa)
- PubMed (publishedVersion)
- Funders
- National Institute of Mental Health (R37MH061345)
- National Institute of General Medical Sciences (GM 20632-01, F32GM020632)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Cellular transport and secretion
- Health Sciences › Medicine › Epidemiology › Autophagy in Disease and Therapy
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Cell Biology › Caveolin-1 and cellular processes
- Keywords
- AP-2, clathrin-mediated endocytosis, AAK1, clathrin coat assembly, adenoviral overexpression
- MeSH terms
- Clathrin, Coated Pits, Cell-Membrane, Endocytosis, HeLa Cells, Humans, Phosphorylation, Recombinant Fusion Proteins, Transferrin, Adaptor Protein Complex 2
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