Members of theRassuperfamily of small GTPases (p21) are involved in the regulation of a large variety of key cellular processes, including cell differentiation and proliferation, membrane trafficking, and nuclear import and export. Based on sequence homology, this superfamily can be divided into the Ras, Rho, Ran, Arf, Rab, and Rad subfamilies, which all have distinct biological activities. All members of this superfamily act as molecular switches and become activated and capable of transducing a signal upon binding to GTP, while guanosine triphosphate (GTP) hydrolysis returns them to the inactive state. Most members of this superfamily are post-translationally modified and carry isoprenoids at their C-termini, which anchors them to the membrane.
