Phosphatidylinositol-3,4,5-Trisphosphate Dependent Rac Exchange Factor 1 (PREX1)

PREX1 acts as a guanine nucleotide exchange factor for the RHO family of small GTP-binding proteins (RACs). It has been shown to bind to and activate RAC1 by exchanging bound GDP for free GTP. The encoded protein, which is found mainly in the cytoplasm, is activated by phosphatidylinositol-3,4,5-trisphosphate and the beta-gamma subunits of heterotrimeric G proteins.PREX1 has a tandem DH/PH domain typical of RHO family GEFs, 2 DEP and 2 PDZ domains, and significant similarity over its C-terminal half to inositol polyphosphate 4-phosphatase. Northern blot analysis detected expression of a 6-kb major transcript and a slightly smaller minor transcript mainly in peripheral blood leukocytes and brain, with lower expression in spleen and lymph nodes and much weaker expression in most other tissues.