Functions in an early step of clathrin-mediated endocytosis (PubMed:30822429). 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 (PubMed:30822429, PubMed:32098969). Affects TCR clustering upon receptor triggering and modulates its internalization, playing a role in TCR-dependent T-cell activation (PubMed:32098969). {ECO:0000269|PubMed:20448150, ECO:0000269|PubMed:30822429, ECO:0000269|PubMed:32098969}. This is the function of FCHO1 (FCH and mu domain containing endocytic adaptor 1, ENSG00000130475).