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. 1997 May 27;94(11):5656–5661. doi: 10.1073/pnas.94.11.5656

Figure 1.

Figure 1

cAMP accumulation and β-adrenergic receptor binding in S49 cyc cells transfected with wild type or mutant αs. (A) cAMP accumulation in intact cells. S49 cyc cells stably transfected with HA-αs or HA-αs-R231H were incubated at 37°C for 30 min with 100 nM 3-isobutyl-1-methylxanthine and 10 μM isoproterenol (▪) or no drug (□ and ▨) and cAMP accumulation was measured (21). Cholera toxin (1 μg/ml; ▨) was added to the culture medium 3 h before adding IBMX. Values represent mean ± SD of triplicate determinations. (B) Competition between isoproterenol and [125I]pindolol for binding the β-adrenergic receptor. Membranes (0.15 mg/ml) of S49 cyc cells stably transfected with HA-αs or HA-αs-R231H were incubated with [125I]pindolol (72 pM) and the indicated concentrations of isoproterenol in the presence (open symbols) or absence (filled symbols) of 30 μM GTP[γS]; incubations and binding assays were performed as described (22).