FIGURE 7.
Role of receptor phosphorylation in D2 DAR desensitization. HEK293T cells were transfected with either WT or GRK(-) mutant D2L DARs. Cells were preincubated in the absence or presence of 10 μm DA for the indicated times followed by membrane preparation and [35S]GTPγS binding assays as described under “Experimental Procedures.” A and B, amount of DA-stimulated [35S]GTPγS binding is expressed as the percent maximum observed in the control (no DA pretreatment) group. Single representative experiments are shown, which were replicated three times with identical results. C, maximum binding for each DA treatment group was plotted versus preincubation time. The data are expressed as a percentage of the control (no DA pretreatment) and represent the mean ± S.E. values from three independent experiments. *, p < 0.03 compared with WT at the time of 60 min of preincubation, unpaired Student's t test.