Phosphorylation of an inositol phosphate-stimulated protein phosphatase by protein kinase C.

It is shown that the catalytic subunit of an inositol phosphate-stimulated protein phosphatase (a member of the type-1 protein phosphatase family) purified from bovine brain membranes is phosphorylated in vitro by protein kinase C, but not by protein kinase A or by Ca2+/calmodulin-dependent protein kinase II. The phosphorylation of the protein phosphatase by protein kinase C induces an increased sensitivity to stimulation by Ins (1,4,5)P3, Ins(1,3,4,5,6)P5 and heparin.