Proteins containing this domain include FARP1, FARP2 and FRMD7. FARP1 and FARP2 are members of the Dbl family guanine nucleotide exchange factors (GEFs) which are upstream positive regulators of Rho GTPases []. FARP1 has increased expression in differentiated chondrocytes. FARP2 is thought to regulate neurite remodeling by mediating the signaling pathways from membrane proteins to Rac. It is found in brain, lung, and testis, as well as embryonic hippocampal and cortical neurons []. They are composed of a N-terminal FERM domain, a proline-rich (PR) domain, Dbl-homology (DH), and two C-terminal PH domains.FRMD7 (FERM domain-containing protein 7) and Caenorhabditis elegans CFRM3 have a FERM domain that is closely related to that in FARP1 and FARP2. Both have unknown functions. They contain an N-terminal FERM domain, a PH domain, followed by a FA (FERM adjacent) domain []. FRMD7 has been linked to Idiopathic congenital nystagmus , an infant-onset disease with the typical features of bilateral ocular oscillations, visual impairment, and abnormal head movement []. The FERM domain has a cloverleaf tripart structure composed of: (1) FERM_N (A-lobe or F1); (2) FERM_M (B-lobe, or F2); and (3) FERM_C (C-lobe or F3). The C-lobe/F3 within the FERM domain is part of the PH domain family. Like most other ERM members they have a phosphoinositide-binding site in their FERM domain. The FERM C domain is the third structural domain within the FERM domain. The FERM domain is found in the cytoskeletal-associated proteins such as ezrin, moesin, radixin, 4.1R, and merlin. These proteins provide a link between the membrane and cytoskeleton and are involved in signal transduction pathways. The FERM domain is also found in protein tyrosine phosphatases (PTPs) , the tyrosine kinases FAK and JAK, in addition to other proteins involved in signaling. This domain is structurally similar to the PH and PTB domains and consequently is capable of binding to both peptides and phospholipids at different sites [, ].
