Figure 5. PDEs encoded by Drosophila PDE genes exhibit cG- and cA-PDE activity.

PDEs were immunoprecipitated from adult Drosophila head lysates using affinity-purified antibodies (PDE1, PDE6 and PDE9) and whole serum (PDE11). Control IPs were performed with IgG (preimmune serum for PDE11). Each immunoprecipitated sample was assayed for cGMP- and cAMP-specific PDE activity, where cG-PDE activity is indicated by unshaded bars; and cAMP-PDE activity is indicated by shaded bars. For each PDE, activities were assessed under the conditions described in the x-axis for each graph: (A) PDE1, (B) PDE6, (C) PDE9 and (D) PDE11. PDE activities were assayed at either 10 μM cGMP (for cG-PDE activity) or 10 μM cAMP (for cA-PDE activity). Ca²⁺/calmodulin-stimulated PDE1 activity was assayed at 0.2 mM Ca²⁺ and 0.4 mg/ml calmodulin. Data are represented as PDE activity [pmol of cGMP or cAMP·(IP assay)⁻¹·min⁻¹±S.E.M., n=6]. cG-PDE activity in the IgG-treated fraction from PDE1 samples (A) was negligible. *, Data statistically significant between antibody-specific and control IPs, assayed for cG- and cA-specific PDE activity, where P<0.05 (Student's unpaired t test). Additionally, in PDE1 panel, * indicates statistical significance (P<0.05, Student's unpaired t test) between EGTA-treated (0.1 mM EGTA) and untreated samples assayed for cG-PDE activity.