 The lipid ligand is coordinated by residues from surrounding alpha-helices and all three phosphates are multiply coordinated.Proteins containing this domain have been found to bind PtdIns(4,5)P2 and Ins(1,4,5)P3 suggesting that the domain is a membrane-interacting module.The main function of proteins containing this domain appears to be to act as accessory clathrin adaptors in endocytosis, epsin is able to recruit and promote clathrin polymerisation on a lipid monolayer, but may have additional roles in signalling and actin regulation.