Intrinsic Activity of Guanosine 3′,5′-Monophosphate-dependent Protein Kinase Similar to Adenosine 3′,5′-Monophosphatedependent Protein Kinase

Abstract

Guanosine 3′,5′-monophosphate (cyclic GMP)-dependent protein kinase partially purified from silkworm pupae reacts preferentially with H1, H2A, and H2B histones but not with H3 and H4 histones. However, the latter can serve as substrates in the presence of a stimulatory modulator as described by Kuo and Kuo (J.Biol.Chem 251, 4283–4286 (1976)).With H2B histone as substrate high Mg²⁺ concentrations (50–100 him) are necessary for the maximum rate of reaction.Although effects of the modulator and Mg²⁺ vary significantly with the histone fractions employed, analysis on the phosphorylation of histone fractions provides evidence that cyclic GMP-dependent protein kinase possesses an intrinsic activity that is similar to that of adenosine 3′,5′-monophosphate-dependent protein kinase.