AP-2 complex subunit alpha-1 (P17426)

Uniprot ID P17426
Protein Name AP-2 complex subunit alpha-1
Gene Name Ap2a1
Species Mus musculus (Mouse)
Signal peptide(a) N Secretome P(b) 0.449
Function Component of the adaptor protein complex 2 (AP-2). Adaptor protein complexes function in protein transport via transport vesicles in different membrane traffic pathways. Adaptor protein complexes are vesicle coat components and appear to be involved in cargo selection and vesicle formation. AP-2 is involved in clathrin-dependent endocytosis in which cargo proteins are incorporated into vesicles surrounded by clathrin (clathrin-coated vesicles, CCVs) which are destined for fusion with the early endosome. The clathrin lattice serves as a mechanical scaffold but is itself unable to bind directly to membrane components. Clathrin-associated adaptor protein (AP) complexes which can bind directly to both the clathrin lattice and to the lipid and protein components of membranes are considered to be the major clathrin adaptors contributing the CCV formation. AP-2 also serves as a cargo receptor to selectively sort the membrane proteins involved in receptor-mediated endocytosis. AP-2 seems to play a role in the recycling of synaptic vesicle membranes from the presynaptic surface. AP-2 recognizes Y-X-X-[FILMV] (Y-X-X-Phi) and [ED]-X-X-X-L-[LI] endocytosis signal motifs within the cytosolic tails of transmembrane cargo molecules. AP-2 may also play a role in maintaining normal post-endocytic trafficking through the ARF6-regulated, non-clathrin pathway. The AP-2 alpha subunit binds polyphosphoinositide-containing lipids, positioning AP-2 on the membrane. The AP-2 alpha subunit acts via its C-terminal appendage domain as a scaffolding platform for endocytic accessory proteins. The AP-2 alpha and AP-2 sigma subunits are thought to contribute to the recognition of the [ED]-X-X-X-L-[LI] motif (By similarity). .
GO - Molecular function
  • clathrin adaptor activity : IEA:InterPro
  • low-density lipoprotein particle receptor binding : ISO:MGI
  • protein C-terminus binding : ISO:MGI
  • protein kinase binding : IPI:ParkinsonsUK-UCL
  • protein-containing complex binding : ISO:MGI
GO - Biological process
  • clathrin-dependent endocytosis : IEA:InterPro
  • intracellular protein transport : TAS:MGI
  • negative regulation of hyaluronan biosynthetic process : ISS:UniProtKB
  • positive regulation of neuron projection development : ISO:MGI
  • positive regulation of receptor-mediated endocytosis : ISO:MGI
  • vesicle-mediated transport : TAS:MGI
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(a) The Signal peptide D-score cutoff for "YES"(having signal peptide) is 0.45.
(b) Non-classically secreted proteins should obtain an NN-score(Neural Networks score) exceeding the normal threshold of 0.5, but not at the same time be predicted to contain a signal peptide.