Figure 8.
G-protein-coupling properties of cross-linked mutant M3R dimers. COS-7 cells were transfected with the indicated receptor constructs or vector DNA. Subsequently, cell membranes were incubated in the absence or presence of Cu-Phen (100 μM). To compare the G-protein-coupling properties of the non-cross-linked and cross-linked (Cu-Phen-treated) receptors, cell membranes were treated with the agonist carbachol (CCh; 1 mM) in the presence of [35S]-GTPγS for 2 min at 30°C. Agonist-stimulated [35S]-GTPγS binding was assessed by selective immunoprecipitation of [35S]-GTPγS-labeled Gαq/11, using an anti-Gαq/11 antiserum. Data are shown as means ± se of 3 separate experiments, each carried out in duplicate. **P < 0.01 vs. absence of Cu-Phen pretreatment on CCh response of 264C M3R.