title: Separation of mercury substituted RNA synthesized in isolated rat liver nuclei.
abstract: The population of RNA molecules synthesized in isolated rat liver nuclei in vitro in the presence of [3H]CTP and Hg-UTP was successfully fractionated into at least two subfractions containing various proportions of mercury label. Fractionation was achieved either by step-wise chromatography of Hg-RNA on thiopropyl-Sepharose columns or by density gradient centrifugation in metrizamide. The fraction of RNA heavily labeled with Hg-UTP was composed mainly of 4--18S RNA and contained virtually all radioactivity derived from [gamma-32P]ATP or [gamma-32P]GTP. The slightly mercurated RNA fraction consisted mainly of longer RNA molecules (12- greater than 28S) and was not labeled with [gamma-32P]ATP or [gamma-32P]GTP. Labeling with gamma-32P nucleoside triphosphates was sensitive both to rifamycin AF/013 and heparin whereas labeling with [3H]CTP was fully resistant to the inhibitors and showed sensitivity to low doses of alpha-amanitin. We assume that the observed subpopulation of heavily mercurated RNAs consists of RNA molecules initiated in vitro.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D002499:Centrifugation, Density Gradient; D002850:Chromatography, Gel; D003570:Cytidine Triphosphate / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008628:Mercury / Q000378:metabolism*; D008793:Metrizamide; D012313:RNA / Q000378:metabolism*; D051381:Rats; D014158:Transcription, Genetic; D014544:Uridine Triphosphate / Q000378:metabolism
chemical_list: D012313:RNA; D003570:Cytidine Triphosphate; D008628:Mercury; D008793:Metrizamide; D014544:Uridine Triphosphate