Figure 5.

The effect of RGS4 and GAIP on adenylyl cyclase activity in NG-108 membranes. NG-108 membranes and the indicated concentrations of RGS4 (open symbols) or GAIP (filled symbols) were incubated for 15 min at 4°C. Adenylyl cyclase activity in these membranes was then measured as described under Materials and Methods in the presence of 10 μM PGE₁ (circles) or 10 μM PGE₁ + 2 μM [Leu]enkephalin (squares). The data shown are averages of duplicates determinations from a single experiment, which is representative of three experiments.