A 5′-Adenosine Monophosphate-Dependent Adenylate Cyclase and an Adenosine 3′:5′-Cyclic Monophosphate-Dependent Adenosine Triphosphate Pyrophosphohydrolase in <i>Dictyostelium discoideum</i>

Abstract

Cell aggregation in Dictyostelium discoideum appears to involve the production and detection of 3':5'-cyclic AMP. Two pertinent catalytic activities have been studied in concentrates from D. discoideum purified 50- to 100-fold. They are (i) adenylate cyclase and (ii) ATP pyrophosphohydrolase. ATP pyrophosphohydrolase activity converts ATP to 5'-AMP and pyrophosphate. The presence of 5'-AMP is an absolute requirement for adenylate cyclase activity. The presence of 3':5'-cyclic AMP is an absolute requirement for ATP pyrophosphohydrolase activity. Both activations, particularly that of ATP pyrophosphohydrolase, show narrow ranges of specificity and display significant cooperativities.