ADENYLATE-CYCLASE ACTIVITY FROM HIRUDO-MEDICINALIS SEGMENTAL GANGLIA - MODULATION BY CALCIUM AND CALMODULIN

An adenylate cyclase activity stimulated by serotonin and calmodulin i s present in the segmental ganglia of the leech Hirudo medicinalis. Re moval of the endogenous calcium binding protein does not alter the res ponsiveness of the enzyme to serotonin. The calmodulin antagonist, tri fluoperazine, drastically reduces the amine stimulatory effect on both intact and calmodulin-depleted membranes. We suggest that calmodulin- sensitive and serotonin-stimulated adenylate cyclase are, at least fun ctionally, independent.