title: Ornithine decarboxylase may function as an initiation factor for RNA polymerase I.
abstract: Reparts suggest that the activity of RNA polymerase I is modulated by a labile protein with a hlaf-life of 10 to 20 minutes. Ornithine decarboxylase is the only labile protein (half-life, 10 to 20 minutes) that increases in activity prior to increased RNA polymerase I activity. The addition of a small amount of a highly purified ornithine decarboxylase preparation to an RNA polymerase I assay increases the initial rate of the reaction as well as the time for which the assay is linear. The incorporation patterns of 14C-labeled adenosine triphosphate and 32P-labeled adenosine triphosphate into RNA indicate that the addition of ornithine decarboxylase to the RNA polymerase assay increases the rate of initiation. This report demonstrates a novel way to purify ornithine decarboxylase by RNA polymerase I affinity chromatography and presents data in support of the hypothesis that the labile protein which modulates RNA polymerase I activity is ornithine decarboxylase.
mesh_terms: D000818:Animals; D002262:Carboxy-Lyases / Q000494:pharmacology*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004789:Enzyme Activation; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D009955:Ornithine Decarboxylase / Q000302:isolation & purification / Q000494:pharmacology*; D012318:RNA Polymerase I / Q000378:metabolism*; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases; D012318:RNA Polymerase I; D002262:Carboxy-Lyases; D009955:Ornithine Decarboxylase