FERM domains recruit ample PI(4,5)Ps to form extensive protein-membrane attachments.

The four-point-one ezrin-radixin-moesin homology (FERM) protein domain is a multifunctional protein-lipid binding site, constituting an integral part of numerous membrane-associated proteins. Its interaction with the lipid phosphatidylinositol-4,5-bisphosphate (PIP), located at the inner leaflet of eukaryotic plasma membranes, is important for localization, anchorage, and activation of FERM-containing proteins. FERM-PIP complexes structurally determined so far exclusively feature a 1:1 binding stoichiometry of protein and lipid, with a few basic FERM residues neutralizing the -4 charge of the bound PIP.