<p>The adaptor protein complexes mediate both the recruitment of clathrin to membranes and the recognition of sorting signals within the cytosolic tails of transmembrane cargo molecules. The adaptor protein complex 2 (AP-2) appears to play a role in the recycling of synaptic vesicle membranes from the presynaptic surface.</p> <p>AP-2 is a heterotetramer composed of two large adaptins (alpha-type subunit AP2A1 or AP2A2 and beta-type subunit AP2B1), a medium adaptin (mu-type subunit AP2M1) and a small adaptin (sigma-type subunit AP2S1). It is a component of a complex composed at least of ACTB, AP2M1, AP2A1, AP2A2, MEGF10 and VIM, which interacts with RAB11FIP2. The subunits of clathrin-associated adaptor protein complex 2 play a role in protein sorting in the late-Golgi/trans-Golgi network (TGN) and/or in endosomes. </p><p>This group represents an adaptor protein complex AP-2, alpha subunit.</p>