FIGURE 3.

PDE11 is stimulated by cGMP analogue but not by cGMP. Stimulation (stim.) of recombinant PDE11 holoenzyme by the cGMP analogue Rp-8-pCPT-PET-cGMPS was assessed at the indicated concentrations of the substrates cAMP (A) and cGMP (B). High cAMP or cGMP concentrations (100 μm) did not impair the 4–5-fold stimulation by the GAF domain ligand. C, measurement of cAMP hydrolysis at the indicated substrate concentrations in the presence of increasing concentrations of cGMP reveals no stimulation but only competitive inhibition. Means ± standard error of the mean of three independent experiments performed in duplicates are shown after normalization to the activity observed in the absence of Rp-8-pCPT-PET-cGMPS (A and B) or cGMP (C) at the substrate concentrations indicated.