Fig. 4. Examples of Rho regulation by membrane localization. (A) Schematic presentation of elements in Rho that dictate membrane targeting. (B) Membrane delivery of Rho protein by Rho-complexed RhoGDI binding to target molecules at specific membrane sites followed by release of Rho protein to the membrane. (C) The polybasic domain found in some Rho-family proteins provides a second signal that dictates membrane localization. The components in the membranes (here depicted as `X' and `Y') that specifically bind to and localize each Rho protein (here examplified by the names `Rho1' and `Rho2') are unknown. Abbreviations: PM, plasma membrane; EM, endomembrane.