Figure 2

[³⁵S] GTPγS binding for the two α _2B -ARs in PC12 cells. A. PC12 cells were exposed to vehicle (Control) or 10 μM UK14304 (Agonist-pretreated) and agonist-stimulated [35S] GTPγS binding was determined. Results are expressed as % of basal binding, indicating a ~ 53% desensitization of the WT α_2B-AR (see also Table 1). *, p < 0.05, vs. Control WT α_2B-AR, n = 6 independent experiments. B. Membranes from control (Control) and 10 μM epinephrine-pretreated (Epi) cells were incubated with increasing concentrations (c) of epinephrine. Only the Epi-pretreated WT α_2B-AR displays decreased [³⁵S] GTPγS binding (i.e. desensitization) in response to Epi, whereas the Del α_2B-AR fails to do so. *, p < 0.05, vs. Epi, n = 6 independent experiments.