Multiple Ca2+signaling pathways converge on CaM kinase in PC12 cells

The role of multifunctional Ca2+/calmodulin‐dependent protein kinase (CaM kinase) in mediating various Ca2+signaling pathways was examined in PC12 cells. Conversion of the kinase to a Ca2+‐independent form was used to monitor which neurotransmitters activate the enzyme in situ. CaM kinase responds to Ca2+influx elicited by ligand‐gated Ca2+channels for ATP and acetylcholine. It also responds to Ca2+mobilization ofIP3‐sensitive stores elicited by phospholipase C‐linked receptors for ATP and acetylcholine as well as by caffeine. CaM kinase mediates the actions of many neurotransmitters and Ca2+signaling pathways.