Functions as a RAC1 guanine nucleotide exchange factor (GEF), activating Rac proteins by exchanging bound GDP for free GTP. Its activity is synergistically activated by phosphatidylinositol 3,4,5-trisphosphate and the beta gamma subunits of heterotrimeric G protein. Mediates the activation of RAC1 in a PI3K-dependent manner. May be an important mediator of Rac signaling, acting directly downstream of both G protein-coupled receptors and phosphoinositide 3-kinase.
Isoform 1 is highly expressed in skeletal muscle, heart and placenta, absent from peripheral blood leukocytes. Isoform 2 is expressed in skeletal muscle, kidney, small intestine, and placenta. Isoform 3 is expressed in the heart.