Characterization of a CK II protein kinase from etiolated oat seedlings.
Protein kinases play a central role in controlling the cellular metabolism of living organisms. A protein kinase was purified from etiolated oat seedlings by several steps of ion-exchange and affinity chromatographies. The kinase was a 150-kDa tetrameric protein and composed of three subunits of 34, 37, and 40 kDa proteins. The 34 and 40 kDa proteins had ATP binding sites, suggesting that they are catalytic subunits and that the 37-kDa protein is a regulatory subunit. In the in vitro phosphorylation of a crude oat cell extract, it intensively phosphorylated a serine residue of a 110-kDa protein. The 110-kDa protein was tentatively identified as a DNA topoisomerase I, based on an amino acid sequence homology. Phosphorylation of the 110-kDa protein by the kinase required ATP or GTP as a phosphoryl group donor. The kinase activity was inhibited by 50% at a concentration of 0.05 microg/ml heparin. These results, therefore, indicate that the purified kinase is a CK II protein kinase and may be involved in the regulation of DNA topoisomerase I activity.
Kim
Sang-Yeob
SY
Department of Genetic Engineering, College of Natural Science, Kyungpook National University, Daegu, Korea.
Kim
Yong-Woo
YW
Kim
Dong-Kyoon
DK
Kwak
Su-Nam
SN
Kim
In-Soo
IS
D018554:Avena / Q000201:enzymology / Q000235:genetics*; D047390:Casein Kinase II; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011107:Polylysine / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D036226:Seedlings / Q000201:enzymology / Q000235:genetics*
D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D011107:Polylysine; D006493:Heparin; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases