RGS19, also known as Regulator of G-protein signaling 19, belongs to RGS (regulator of G protein signaling) family and negatively regulates G protein coupled receptor signaling. This protein specifically interacts with heterotrimeric GTP-binding protein G alpha i3 (GAI3). Recombinant human RGS19 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography.