AP2B1

The protein encoded by this gene is one of two large chain components of the assembly protein complex 2, which serves to link clathrin to receptors in coated vesicles. The encoded protein is found on the cytoplasmic face of coated vesicles in the plasma membrane. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq]

Full Name

adaptor-related protein complex 2, beta 1 subunit

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. During long-term potentiation in hippocampal neurons, AP-2 is responsible for the endocytosis of ADAM10 (PubMed:23676497). The AP-2 beta subunit acts via its C-terminal appendage domain as a scaffolding platform for endocytic accessory proteins; at least some clathrin-associated sorting proteins (CLASPs) are recognized by their [DE]-X(1,2)-F-X-X-[FL]-X-X-X-R motif. The AP-2 beta subunit binds to clathrin heavy chain, promoting clathrin lattice assembly; clathrin displaces at least some CLASPs from AP2B1 which probably then can be positioned for further coat assembly.

Biological Process

Antigen processing and presentation of exogenous peptide antigen via MHC class II Source: Reactome
Aorta development Source: Ensembl
Clathrin coat assembly Source: Ensembl
Clathrin-dependent endocytosis Source: UniProtKB
Coronary vasculature development Source: Ensembl
Ephrin receptor signaling pathway Source: Reactome
Intracellular protein transport Source: InterPro
Kidney development Source: Ensembl
Low-density lipoprotein particle clearance Source: Reactome
Low-density lipoprotein particle receptor catabolic process Source: Reactome
Membrane organization Source: Reactome
Negative regulation of neuron death Source: Ensembl
Positive regulation of endocytosis Source: Ensembl
Positive regulation of protein localization to membrane Source: Ensembl
Postsynaptic neurotransmitter receptor internalization Source: Ensembl
Regulation of defense response to virus by virus Source: Reactome
Synaptic vesicle endocytosis Source: SynGO
Ventricular septum development Source: Ensembl
Vesicle-mediated transport Source: GO_Central
Wnt signaling pathway, planar cell polarity pathway Source: Reactome

Cellular Location

Cell membrane; Coated pit. AP-2 appears to be excluded from internalizing CCVs and to disengage from sites of endocytosis seconds before internalization of the nascent CCV.

PTM

Phosphorylation at Tyr-737 by SRC occurs at the plasma membrane in clathrin-coated vesicles (CCVs).