Regulator Of G Protein Signaling 21 (RGS21)

Regulator of G protein signaling (RGS) proteins are regulatory and structural components of G protein-coupled receptor complexes. RGS proteins are GTPase-activating proteins for Gi and Gq class G-alpha proteins. The deduced human and rat RGS21 proteins share 87% sequence identity. Phylogenetic and sequence analyses identified RGS21 as the smallest known member of the R4 family. RGS21 shares 57% and 58% sequence identity with RGS1 and RGS2.RT-PCR analysis and in situ hybridization experiments demonstrated that the rat protein is expressed selectively in taste tissue in a subpopulation of sensory cells. In vitro binding assays demonstrated that RGS21 binds alpha-gustducin in a conformation-dependent manner and has the potential to interact with the same G-alpha subtypes as T1R receptors.