Phosphorylation and activation of Ca2+/calmodulin-dependent protein kinasephosphatase by Ca2+/calmodulin-dependent protein kinase II

Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKPase) is a protei n phosphatase which dephosphorylates autophosphorylated Ca2+/calmodulin-dep endent protein kinase II (CaMKII) and deactivates the enzyme (Ishida, A., K ameshita, I, and Fujisawa, H, (1998) J, Biol, Chem, 273, 1904-1910), In thi s study, a phosphorylation-dephosphorylation relationship between CaMKII an d CaMKPase was examined. CaMKPase was not significantly phosphorylated by C aMKII under the standard phosphorylation conditions but was phosphorylated in the presence of poly-L-lysine, which is a potent activator of CaMKPase. The maximal extent of the phosphorylation was about 1 mol of phosphate per mol of the enzyme and the phosphorylation resulted in an about 2-fold incre ase in the enzyme activity. Thus, the activity of CaMKPase appears to be re gulated through phosphorylation by its target enzyme, CaMKII, (C) 1999 Fede ration of European Biochemical Societies.