Rhophilin 2 (RHPN2)

RHPN2 encodes a member of the rhophilin family of Ras-homologous (Rho)-GTPase binding proteins. The encoded protein binds both GTP- and GDP-bound RhoA and GTP-bound RhoB and may be involved in the organization of the actin cytoskeleton. Rhophilin-2 shows 40% amino acid similarity to human Rhophilin-1 and contains an N-terminal Rho-binding, a central Bro1-like, and a C-terminal PDZ domain. Coexpression of Rhophilin-2 with a constitutively active Rho mutant reversed the disassembly phenotype, in which the coexpressing cells were more spread and less contracted than Rho alone-expressing cells. Rhophilin-2 may function normally in a Rho pathway to limit stress fiber formation and/or increase the turnover of F-actin structures in the absence of high levels of RhoA activity.