Binds to membranes enriched in phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). Modifies membrane curvature and facilitates the formation of clathrin-coated invaginations (By similarity). Regulates receptor-mediated endocytosis (By similarity). Monomer. Binds clathrin and ZBTB16/ZNF145 (By similarity). Binds ubiquitinated proteins (By similarity). Interacts with RALBP1 in a complex also containing NUMB and TFAP2A during interphase and mitosis (By similarity). Interacts with AP2B1 (By similarity). Interacts with UBQLN2 (By similarity). Interacts with ITSN1. Interacts with AP2A1 and AP2A2. 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. Detected in presynaptic nerve terminals and in Golgi stacks. May shuttle to the nucleus when associated with ZBTB16/ZNF145 (By similarity). 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. 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. Ubiquitinated. Belongs to the epsin family. The bubble's bend - Issue 42 of January 2004