Formin

In cells the formation of actin filaments is tightly spatially regulated. Formin is a multi-domain protein containing Rho GTPase binding domain (RDB), an profilin-ATP-actin binding domain (FH1) and an filament nucleating domain (FH2). When not bound to Rho the RBD binds and inhibits the FH2 domain. When Rho GTPase becomes activated formin is recruited to the plasmamembrane. This causes a conformational shift which releases the FH1 and FH2 domains to trigger filament formation.