Adaptins are components of the adapter complexes which link clathrin to receptors in coated vesicles. Clathrin-associated protein complexes are believed to interact with the cytoplasmic tails of membrane proteins, leading to their selection and concentration. Binding of AP180 to clathrin triskelia induces their assembly into 60-70 nm coats. Binds AP2A2. Interacts with AP2B1; clathrin competes with SNAP91. Component of the coat surrounding the cytoplasmic face of coated vesicles in the plasma membrane. Possesses a three domain structure: the N-terminal 300 residues harbor a clathrin binding site, an acidic middle domain 450 residues, interrupted by an Ala-rich segment, and the C-terminal domain (166 residues). Thr-310 can be modified by the addition of N-acetylglucosamine which can be further phosphorylated. The form with phosphorylated O-linked N-acetylglucosamine is predominant in brain synaptosomes. There is no evidence for direct Thr-310 phosphorylation (PubMed:21500857). Belongs to the PICALM/SNAP91 family.