Figure 3.

Stimulation of PDE5 by the GAF domain ligand 8-Br-cGMP. (A) PDE5 activity was measured in cytosolic fractions of PDE5 overexpressing HEK cells in the presence of increasing concentrations of 8-Br-cGMP at the indicated concentrations of cGMP as substrate. (B) Activity of a PDE5 construct containing only the catalytic domain was measured at 1 µM cGMP in the presence of increasing concentrations of 8-Br-cGMP or 8-Br-cAMP. The reactions were carried out for 5 min as described in detail in Methods. Data shown are mean ± SD of at least three independent experiments performed in duplicate.