The ezrin, radixin, and moesin (ERM) proteins are general cross-linkers between cortical actin filaments and plasma membranes. They are concentrated at cell surface structures such as microvilli, filopodia, uropods, ruffling membranes, retraction fibers, and cell adhesion sites where actin filaments are associated with plasma membranes, but not along cytoplasmic actin filaments such as stress fibers. ERM proteins also integrate Rho guanosine 5′-triphosphatase (GTPase) signaling to regulate cytoskeletal organization by sequestering Rhorelated proteins. The apparent molecular mass of ERM is 82, 80, and 75 kDa, respectively.  Among the ERM-binding proteins, cell adhesion proteins, CD43, CD44, and intercellular adhesion molecule (ICAM)-2, which contain a single transmembrane domain, bind to the FERM domain of moesin at their juxtamembrane 20–30 amino acid residues in the cytoplasmic domain. ERM proteins also integrate Rho GTPase signaling to regulate cytoskeletal organization by sequestering Rho-related proteins and function as both upstream and downstream effectors of Rho GTPases.  Ezrin (as well as radixin and moesin) also functions as a protein kinase A (PKA)-anchoring protein (AKAP).  ERM proteins seem to play important roles in the membrane transport of electrolytes by ion channels and transporters.

References

1.Kawaguchi K, et al. Biol Pharm Bull. 2017;40(4):381–390.