Figure 5.

Secondary coupling of G_s–coupled dopamine receptors to mGsi and G_i1 heterotrimers. A, recruitment of mG proteins to dopamine receptors. Net BRET between D1R–, D5R–, or D2R–Nluc and four different NES–venus–mG subtypes in response to dopamine (DA) is shown; mean ± S.E. of 5–7 independent experiments. B, recruitment of empty heterotrimers to dopamine receptors. The difference (ΔBRET) between net BRET observed in the presence of 0.5 mm GDP alone and in the presence of apyrase and dopamine (100 μm) is shown. Cells lacking endogenous Gα_s, Gα_q, and Gα₁₂ subunits expressed D1R-, D5R-, or D2R-Rluc8 and heterotrimers consisting of Gβγ–venus and the remaining endogenous Gα subunits (control) or overexpressed Gα_s or Gα_i1. In some experiments cells also expressed the S1 subunit of pertussis toxin (PTX); mean ± S.D. of 3–6 independent experiments.