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

AbstractThe role of RGS proteins on dopaminergic D2S receptor (D2SR) signalling was investigated in Chinese hamster ovary (CHO)-K1 cells, using recombinant RGS protein- and PTX-insensitive Gαo proteins. Dopamine-mediated [35S]GTPγS binding was attenuated by more than 60% in CHO-K1 D2SR cells coexpressing a RGS protein- and PTX-insensitive GαoGly184Ser:Cys351Ile protein versus cells coexpressing a similar amount of PTX-insensitive GαoCys351Ile protein. Dopamine-agonist-mediated Ca2+ responses were dependent on the coexpression with a GαoCys351Ile protein and were fully abolished upon coexpression with a GαoGly184Ser:Cys351Ile protein. These results suggest that interactions between the Gαo protein and RGS proteins are involved in efficient D2SR signalling