Binds to membranes enriched in phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) (PubMed:11161217). Modifies membrane curvature and facilitates the formation of clathrin-coated invaginations (PubMed:9723620, PubMed:12353027). Regulates receptor-mediated endocytosis (By similarity). Monomer. Binds ITSN1 (By similarity). Binds clathrin, ZBTB16/ZNF145, AP2A1 and AP2A2. Binds ubiquitinated proteins. Interacts with RALBP1 in a complex also containing NUMB and TFAP2A during interphase and mitosis. Interacts with AP2B1. Interacts with UBQLN2 (By similarity). Interacts with REPS2; the interaction is direct (By similarity). Interacts with EPS15; the interaction is direct (By similarity). Associated with the cytoplasmic membrane at sites where clathrin-coated pits are forming. Colocalizes with clathrin and AP-2 in a punctate pattern on the plasma membrane. Colocalizes with clathrin at the Golgi complex. Detected in presynaptic nerve terminals and in synaptosomes. May shuttle to the nucleus when associated with ZBTB16/ZNF145. Ubiquitously expressed (PubMed:9723620). Detected in liver, spleen and testis, and weakly in lung and thymus (at protein level) (PubMed:10393179). The NPF repeat domain is involved in EPS15 binding. The DPW repeat domain is involved in AP2A2 and clathrin binding. The [DE]-X(1,2)-F-X-X-[FL]-X-X-X-R motif mediates interaction the AP-2 complex subunit AP2B1. Ubiquitinated. Phosphorylated on serine and/or threonine residues in mitotic cells. Phosphorylation reduces interaction with REPS2, AP-2 and the membrane fraction. Depolarization of synaptosomes results in dephosphorylation. Belongs to the epsin family. The bubble's bend - Issue 42 of January 2004