Fig. 1.

Ras cycles between an active GTP-bound and an inactive GDP-bound conformation. In the active state, the two switch regions, switch I and II, change their conformation allowing Ras to activate effector proteins. The intrinsic GTPase hydrolyzes a phosphate group to produce Ras·GDP. This reaction is accelerated by GTPase activating proteins (GAPs). A similar version of this figure has been previously published [61], republication with permission