RGS3(Regulator of G Protein Signaling 3), is a protein that in humans is encoded by the RGS3 gene. Chatterjee et al.(1997) studied RGS3, the largest member of the RGS family then identified. Mouse Pdz-Rgs3 can mediate signaling from the ephrin-B cytoplasmic tail. By radiation hybrid mapping, Chatterjee et al.(1997) assigned the RGS3 gene to chromosome 9q31-q33. Lu et al.(2001) showed that Sdf1, a chemokine with a G protein-coupled receptor, and Bdnf are chemoattractants for cerebellar granule cells, and that Sdf1 chemoattraction is selectively inhibited by soluble ephrin-B receptor. This inhibition could be blocked by a truncated Pdz-Rgs3 protein lacking the RGS domain.