Functions in an early step of clathrin-mediated endocytosis. Has both a membrane binding/bending activity and the ability to recruit proteins essential to the formation of functional clathrin-coated pits. May regulate Bmp signaling by regulating clathrin-mediated endocytosis of Bmp receptors. Involved in the regulation of T-cell poliferation and activation. Affects TCR clustering upon receptor triggering and modulates its internalisation, playing a role in TCR-dependent T-cell activation. May oligomerize and form homotetramer (PubMed:21762413). Interacts with AP2A2 and AP2B1; 2 subunits of the adaptor protein complex AP-2 (PubMed:22484487). Interacts with DAB2. Interacts with clathrin (CLTC or CLTCL1). Interacts with EPS15, EPS15R and ITSN1. Interacts with AGFG1 and CALM. May interact with ACVR1; linking this receptor to clathrin-mediated endocytosis (By similarity). Associated with forming but not mature clathrin-coated vesicles. The recruitment to coated-pits precede the one of clathrin and the adaptor protein complex AP-2. According to it may also dynamically associate with Golgi/TGN membranes. Mainly detected in brain and spleen. Belongs to the FCHO family.