FIGURE 7.
Effect of catalytic domain mutated or RGS domain-mutated GRK2 on the D1-D2 receptor heteromer-mediated calcium signal. Data represent the percentage of peak fluorescence of the dopamine-induced calcium signal, and values are the means ± S.E. of the numbers shown in brackets below. A, shown is activation of the D1-D2 receptor heteromer-mediated calcium signal by 10 μm dopamine in cells without or with expression of 2.5 or 5 μg of cDNA for GRK2 (third and sixth bars), GRK2-K220R (fourth and seventh bars), or GRK2 D110A (fourth and eight bars) (n = 3–5). B, shown is an immunoblot demonstrating the increasing expression of GRK2 and mutated constructs in D1-D2 receptor-expressing cells. GAPDH immunoreactivity was used as a control for protein loading. C, shown is activation of the D1-D2 receptor heteromer-mediated calcium signal with 10 μm dopamine in cells without or with increasing expression of GRK2-R106A/K220R (n = 3). D, shown is an immunoblot demonstrating the increasing expression of GRK2-R106A/K220R. GAPDH immunoreactivity was used as a control for protein loading. A significant difference from control is denoted by * = p < 0.05.