A growing family of guanine nucleotide exchange factors is responsible for activation of Ras-family GTPases.

摘要: GTPases of the Ras subfamily regulate a diverse array cellular-signaling pathways, coupling extracellular signals to intracellular response machinery. Guanine nucleotide exchange factors (GEFs) are primarily responsible for linking cell-surface receptors protein activation. They do this by catalyzing dissociation GDP from inactive proteins. GTP can then bind and induce conformational change that permits interaction with downstream effectors. Over past 5 years, approximately 20 novel Ras-family GEFs have been identified characterized. These data indicate variety different signaling mechanisms be induced activate Ras, enabling tyrosine kinases, G-protein-coupled receptors, adhesion molecules, second messengers, various protein-interaction modules relocate and/or elevate Ras-GTP levels. This review discusses structure function catalytic or CDC25 homology domain common almost all GEFs. It also details our current knowledge about regulation rapidly growing family enzymes include Sosl 2, GRF1 CaIDAG-GEF/GRPI-4, C3G, cAMP-GEF/Epac 1 PDZ-GEFs, MR-GEF, RalGDS members, RaIGPS, BCAR3, Smg GDS, phospholipase Cϵ.