High resolution

Module 2: Figure Ras signalling

Function of the monomeric Ras G protein in cell signal transduction.

Ras plays a role as a signal transducer to relay information from various external stimuli to a range of different Ras-dependent responses. When bound to GDP, Ras is inactive. Cell stimuli act through different guanine nucleotide exchange factors (GEFs) such as Son-of-sevenless (SoS), RasGRF and RasGRP to facilitate an exchange of GDP for GTP to create the activated Ras/GTP complex that can relay information through a number of signalling pathways. The action of Ras is terminated by a variety of GTPase-activating proteins (GAPs) that accelerate the ability of Ras to hydrolyse GTP back to GDP.