Abstract
The authors examined the role of the multifunctional Ca super(2+)/calmodulin-dependent protein kinase in regulation of tyrosine hydroxylase. This enzyme, previously characterized from rat brain, is present in PC12, a rat pheochromocytoma cell line. The results implicate a Ca super(2+) -dependent protein kinase as a mediator of both hormonal and electrical stimulation of PC12 cells.