Endogenous RGS proteins facilitate dopamine D2S receptor coupling to Gαo proteins and Ca2+ responses in CHO-K1 cells

Abstract The role of RGS proteins on dopaminergic D 2S receptor (D 2S R) signalling was investigated in Chinese hamster ovary (CHO)-K1 cells, using recombinant RGS protein- and PTX-insensitive G αo proteins. Dopamine-mediated [ 35 S]GTPγS binding was attenuated by more than 60% in CHO-K1 D 2S R cells coexpressing a RGS protein- and PTX-insensitive G αo Gly 184 Ser:Cys 351 Ile protein versus cells coexpressing a similar amount of PTX-insensitive G αo Cys 351 Ile protein. Dopamine-agonist-mediated Ca 2+ responses were dependent on the coexpression with a G αo Cys 351 Ile protein and were fully abolished upon coexpression with a G αo Gly 184 Ser:Cys 351 Ile protein. These results suggest that interactions between the G αo protein and RGS proteins are involved in efficient D 2S R signalling.