Phosphorylation of RNA polymerases: specific association of protein kinase NII with RNA polymerase I.

Abstract

The activities of the three DNA-dependent RNA polymerases from a rapidly growing rat tumour, Morris hepatoma 3924A, and from rat liver were examined. The activity of RNA polymerase I was higher in the tumour than in the liver. The enhanced capacity for RNA synthesis was a result of a higher concentration of polymerase I in the tumour as well as of an activation of this enzyme in vivo. The possibility that the high specific activity of the hepatoma polymerase I resulted from phosphorylation was investigated. Two major cyclic-AMP-independent nuclear casein kinases (NI and NII) were identified; the activity of protein kinase NII in the tumour was ten times that in liver. Protein kinase NII was capable of activating and phosphorylating RNA polymerase I in vitro. This kinase could also stimulate RNA polymerase II activity, although to a lesser extent than RNA polymerase I. RNA polymerase III was not affected by protein kinase NII. Protein kinase NII was tightly associated with polymerase I and was found even in purified preparations of the polymerase. Antibodies against both RNA polymerase I and protein kinase NII were present in sera of patients with certain rheumatic autoimmune diseases. These results imply that RNA polymerase I and protein kinase NII are in close association in vivo as well as in vitro and that polymerase phosphorylation may regulate the rate of ribosomal RNA synthesis in the cell.

• Authors: K M Rose, D A Stetler, S T Jacob
• Journal: Philosophical transactions of the Royal Society of London. Series B, Biological sciences (Philos Trans R Soc Lond B Biol Sci) Vol. 302 Issue 1108 Pg. 135-42 (Jul 05 1983) ISSN: 0962-8436 [Print] England
• PMID: 6137001 (Publication Type: Journal Article, Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Cyclic AMP
• Protein Kinases
• Casein Kinases
• RNA Polymerase II
• DNA-Directed RNA Polymerases
• RNA Polymerase I
• RNA Polymerase III

Topics

• Animals
• Casein Kinases
• Cyclic AMP (metabolism)
• DNA-Directed RNA Polymerases (metabolism)
• Liver (enzymology)
• Liver Neoplasms, Experimental (enzymology)
• Phosphorylation
• Protein Kinases (metabolism)
• RNA Polymerase I (metabolism)
• RNA Polymerase II (metabolism)
• RNA Polymerase III (metabolism)
• Rats