Purification and properties of a cyclic AMP-independent protein kinase from calf thymus nuclei.
A phosphoprotein kinase (ATP : protein phosphotransferase, EC 2.7.1.37) from calf thymus nuclei was purified by DEAE-cellulose chromatography, hydroxyapatite, and Sepharose 6B gel filtration. The enzyme is a cyclic AMP-independent protein kinase by the following criteria: (a) the protein kinase did not bind cyclic AMP; (b) no inhibition of activity was obtained with the heat-stable protein kinase inhibitor from rabbit skeletal muscle; (c) the regulatory subunit of cyclic AMP-dependent protein kinase had no effect on activity; and (d) no inhibition was obtained with antibody to cyclic AMP-dependent protein kinase. The nuclear cyclic AMP-independent protein kinase readily phosphorylated protamine on serine and to a lesser extent on threonine. Homologous nucleoplasmic RNA polymerase (EC 2.7.7.6) is a better substrate than arginine-rich histone, phosvitin or casein. Physical characteristics of the enzyme are described.
D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D002417:Cattle; D002467:Cell Nucleus / Q000201:enzymology; D000242:Cyclic AMP / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D011494:Protein Kinases / Q000302:isolation & purification* / Q000378:metabolism; D012492:Salts / Q000494:pharmacology; D013379:Substrate Specificity; D013950:Thymus Gland / Q000201:enzymology*
D002413:Cations, Divalent; D012492:Salts; D000242:Cyclic AMP; D011494:Protein Kinases