VAV2: Proteins and Enzymes

The Vav family are Rho/Rac guanosine nucleotide exchange factors (GEFs), consisting of three members in mammalian cells (Vav, Vav2, Vav3) and one in nematodes (CelVav) (1). Vav and Vav2 are members of the dbl family of guanine nucleotide exchange factors (GEF) for the rho/rac family of GTP binding proteins. Vav is expressed primarily in hematopoietic cells, while vav2 has a wider tissue distribution (2). Vav2 serves as a guanine nucleotide exchange factor for the Rho family of Ras-related GTPases. Unlike Vav1, whose expression is restricted to cells of hematopoietic origin, Vav2 is broadly expressed. Recently, Vav2 has been identified as a substrate for the epidermal growth factor (EGF) receptor. EGF receptor phosphorylates Vav2 on all three possible phosphorylation sites, Tyr-142, Tyr-159, and Tyr-172. results suggest that EGF regulates Vav2 activity basically through phosphatidylinositol 3-kinase activation, whereas tyrosine phosphorylation of Vav2 may rather be necessary for mediating protein-protein interactions (3)