FIGURE 6.

Activated transducin reverses the inhibition of truncation mutants, but not C-terminal peptide Pγ63–87. Purified Pαβ (1 nm) was incubated with 10 nm Pγ1–87, 30 nm Pγ1–86, 30 nm Pγ1–85, 30 nm Pγ1–73, 10 μm Pγ63–87, or a mixture of 10 μm Pγ63–87 and 0.25 μm Pγ1–70 for 5 min at room temperature. The activated transducin α-subunit (9 μm) was added to the above mixture, followed by the addition of 0.1 mm [³H]cAMP for PDE activity measurements. The PDE activity was expressed as the percentage of Pαβ activity in the absence of Pγ peptides. The data are the means ± S.D. of three experiments, except Pγ63–87 and Pγ1–70 where n = 2. The asterisks indicate that the PDE activity in the presence of transducin was statistically significant (p < 0.01) compared with the control, in which no transducin was added.