Adapter protein that plays a role in endocytosis via clathrin-coated pits. Contributes to the internalization of cell surface receptors, such as integrin ITGB1 and transferrin receptor (PubMed:29887380). Promotes endocytosis of EGFR in cancer cells, and thereby contributes to the down-regulation of EGFR signaling (PubMed:30249660). Recruited to clathrin-coated pits during a mid-to-late stage of assembly, where it is required for normal progress from U-shaped intermediate stage pits to terminal, omega-shaped pits (PubMed:29887380). Binds to membranes enriched in phosphatidylinositol 3,4-bisphosphate or phosphatidylinositol 3,4,5-trisphosphate (PubMed:29887380). When bound to membranes, promotes actin polymerization via its interaction with WAS and/or WASL which leads to the activation of the Arp2/3 complex. Does not promote actin polymerisation in the absence of membranes (PubMed:29887380). Homodimer (PubMed:29887380). Interacts (via SH3 domain 2) with ITSN1 (via SH3 domain 4). Recruited to clathrin-coated pits during a mid-to-late stage of assembly via interaction with ITSN1. Interacts (via SH3 domain 1) with WASL (PubMed:29887380). Interacts with WAS (By similarity). Interacts with CASK and MAGI1. CASK inhibits interaction with MAGI1 (PubMed:14627983). Partially localized at clathrin-coated pits at the cell membrane (PubMed:30249660). Detected at the cell membrane at sites around clathrin-coated pits, very close to the clathrin-coated pits but not an intrinsic part of the clathrin-coated pits (PubMed:29887380). Colocalizes at cell-cell contacts with CDH1, but is not detected at tight junctions (PubMed:14627983). Liver, brain, heart, placenta, skeletal muscle, pancreas, lung and kidney. The F-BAR domain has an atypical, flat shape and binds preferentially to flat membranes. Upon heterologous expression, the isolated F-BAR domain is localized at the cell membrane, and causes the formation of cellular protrusions. Recruited to clathrin-coated pits via SH3 domain 2. The two SH3 domains cooperate to maintain the protein in an autoinhibited conformation that prevents promiscuous membrane binding. Phosphorylated. Phosphorylation on a Ser residue is important for recruitment to the cell membrane and for its role in promoting endocytosis. The function in endocytosis may depend on the cell type. Plays a role in EGFR endocytosis via clathrin-coated pits in cancer cells, but apparently not in normal cells (PubMed:30249660). A later study used both HeLa cells and BSC1 cells (a C.aethiops kidney cell line), and did not mention any cell-type specific effects (PubMed:29887380).