Diabetes · 1980 · 78 citations · 0 references
Life SciencesBiochemistryPhysiologyCalcium HomeostasisCell SignalingSignal TransductionCalcium SignalingCarbohydrate MetabolismCyclic Nucleotide SignalingIntracellular Calcium SignalingPancreatic EndocrinologyPancreatic HormonesAdenylate Cyclase RegulationAdenylate Cyclase SignalingAdenylyl Cyclase RegulationCalcium-calmodulin SignalingCalcium-mediated SignalingCalmodulin-mediated RegulationCamp SignalingCyclic Adenosine Monophosphate Signaling
The effect of Ca2+ and calmodulin has been studied on adenylate cyclase activity in homogenates of rat islets of Langerhans. EGTA had a stimulatory effect on the enzyme in accord with the known inhibitory effect of Ca2+. In contrast, the addition of Ca2+ together with calmodulin is stimulatory and demonstrates the existence of a Ca2+-dependent adenylate cyclase in islets of Langerhans. It is suggested that the glucose-induced increase in cyclic AMP concentrations in intact islets is a secondary consequence of the glucose-induced increase in cytosol free-Ca2+ concentrations which, with calmodulin, causes an increase in the activity of adenylate cyclase.