Fig. 4.
Inhibition of AC activity in vitro. (A) The effects of 100 µM NKY80, SKF-83566, and tranilast on forskolin-stimulated (30 µM) AC activity were measured in membranes of Sf9 cells expressing AC1, AC2, or AC5. **P < 0.01 (t test compared with vehicle condition). (B) Chemical structures of NKY80, SKF-83566, and tranilast. (C) Double-reciprocal plot of AC activity from Sf9 membranes expressing AC2 (5 µg) in the presence of 100 nM Gαs and in the absence or presence of SKF-83566 (75 µM or 200 µM) and the indicated concentrations of ATP. The data suggest that SKF-83566 noncompetitively inhibited AC2 activity with respect to ATP.