The distribution of the Ca ++-dependent protein activator of cyclic nucleotide phosphodiesterase in invertebrates

Animal species representative of major phyla were found to contain activating factors similar to the Ca ++ binding protein activator of 3′:5′ — cyclic nucleotide phosphodiesterase isolated from bovine heart. These factors are heat stable, non-dialysable and susceptible to proteolysis. All activate bovine heart cyclic nucleotide phosphodiesterase to a comparable extent and all activations are Ca ++ dependent and reversible. The results suggest a ubiquitous distribution and fundamental importance for this Ca ++ binding protein.