Effect of ionic strength on production of cAMP- and Ca2+-independent protein kinase from rat liver plasma membrane.

ABSTRACT

Production of cAMP- and Ca2+-independent protein kinase was stimulated when rat liver plasma membrane was incubated with increasing concentrations of NaCl. This protein kinase release was diminished by addition of protease inhibitor. The molecular mass of this enzyme was approx. 50 kDa and a high concentration of Mg2+ was required for whole histone phosphorylation. These properties are similar to those of the protease-activated form of protein kinase C. The NaCl effect could be replaced by other salts such as LiCl and NaHCO3. These results suggest that membrane-bound protein kinase C is activated by limited proteolysis corresponding to an increase in ionic strength.