AP2S1
Description
The AP2S1 (adaptor related protein complex 2 subunit sigma 1) is a protein-coding gene located on chromosome 19.
AP-2 complex subunit sigma is a protein that in humans is encoded by the AP2S1 gene. One of two major clathrin-associated adaptor complexes, AP-2, is a heterotetramer which is associated with the plasma membrane. This complex is composed of two large chains, a medium chain, and a small chain. This gene encodes the small chain of this complex. Alternative splicing has been observed in this gene and results in two known transcripts.
AP-2 complex subunit sigma, encoded by the AP2S1 gene, is a component of the adaptor protein complex 2 (AP-2), which plays a crucial role in protein transport within cells. AP-2 complexes function by facilitating the movement of proteins via transport vesicles along different membrane traffic pathways. As a vesicle coat component, AP-2 contributes to the selection of cargo and the formation of vesicles. AP-2 is directly involved in clathrin-dependent endocytosis, a process where cargo proteins are packaged into vesicles surrounded by clathrin (clathrin-coated vesicles, CCVs). These CCVs are destined for fusion with the early endosome. While the clathrin lattice acts as a structural scaffold, it cannot bind directly to membrane components. AP complexes, including AP-2, bridge this gap by binding to both the clathrin lattice and the lipid and protein components of membranes, playing a key role in CCV formation. AP-2 also functions as a cargo receptor, selectively sorting membrane proteins involved in receptor-mediated endocytosis. Furthermore, AP-2 seems to be involved in the recycling of synaptic vesicle membranes from the presynaptic surface. AP-2 recognizes specific endocytosis signal motifs (Y-X-X-[FILMV] and [ED]-X-X-X-L-[LI]) within the cytosolic tails of transmembrane cargo molecules. Additionally, AP-2 may participate in maintaining normal post-endocytic trafficking through the ARF6-regulated, non-clathrin pathway. 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. AP-2 may also play a role in extracellular calcium homeostasis.
AP2S1 is also known as AP17, CLAPS2, FBH3, FBHOk, HHC3.
