ADENYLYL CYCLASES AND THE INTERACTION BETWEEN CALCIUM AND CAMP SIGNALING

Adenylyl cyclase is the prototypical second messenger generator. Nearl y all of the eight cloned adenylyl cyclases are regulated by one or ot her arm of the phospholipase C pathway. Functional and ultrastructural investigations have shown that adenylyl cyclases are intimately assoc iated with sites of calcium ion entry into the cell. Oscillations in c ellular cyclic AMP levels are predicted to arise because of feedback i nhibition of adenylyl cyclase by Ca2+. Such findings inextricably inte rtwine cellular signalling by cAMP and internal Ca2+ and extend the kn own regulatory modes available to cAMP.