PURIFICATION OF CA2+/CALMODULIN-DEPENDENT PROTEIN-KINASE-II FROM RAT STOMACH AND ITS LOCALIZATION IN THE MUCOSA

Ca2+/calmodulin-dependent protein kinase II (CaM kinase II) with a M(r) of 530,000 was purified from rat stomach. The enzyme showed a major protein band with 52 kDa and minor components with 50 and 54 kD a when examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The physicochemical and kinetic properties of the enzyme were similar to those of brain CaM kinase II. The enzyme showed a broad substrate specificity, and was capable of phosphorylating several endogenous proteins in the cytosol and membrane fractions. The polyclonal antibody against brain CaM kinase II cross-reacted with the enzyme. Strong immunoreactivity was observed in the parietal cells of stomach by the immunohistochemical investigation. These results suggest that CaM kinase II regulates the Ca2+ dependent cellular functions of the parietal cells.