α-Adaptin is a component of the adaptor protein complex 2 (AP-2). Adaptor protein complexes are vesicle coat components and appear to be involved in cargo selection and vesicle formation. α-Adaptin is involved in clathrin-dependent endocytosis in which cargo proteins are incorporated into vesicles surrrounded by clathrin (clathrin-coated vesicles, CCVs) which are destined for fusion with the early endosome. 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.