Guanine nucleotide exchange factor

In a GTP exchange factor (English guanosine triphosphate exchange factor, GEF) is a signaling protein that acts on a G protein such that this is a bound GDP is exchanged for a GTP. In most cases the G- protein is activated, and thus acts on different effectors. The opponent of the GTP exchange factors are the GTPase active forming proteins (English GTPase -activating proteins, CAP) that activate the GTPase activity of the G protein (which this hydrolyzes the bound GTP cleavage of a phosphate moiety to GDP ). The GTP exchange factors in many biochemical processes play an important role, as without it there is no activity of G- proteins were present. This, in turn, play a crucial role in many signal transduction pathways. Example of G- proteins needed by a GTP exchange factor in order to operate, are proteins of the Ras family, all heterotrimeric G- proteins such as Gs, Gi, Gq, and golf. In humans, about 150 GTP exchange factors are known.