Studies on a cyclic nucleotide-independent protein kinase and its proenzyme in mammalian tissues. II. Proenzyme and its activation by calcium-dependent protease from rat brain.

was found in the soluble fraction of rat brain.Upon limited proteolysis by calcium-dependent protease occurring in the same tissue, the proenzyme was converted to an active protein kinase which could phosphorylate five species of histone fractions.Trypsin also catalyzed the conversion.