DNA-Dependent RNA Polymerase C. Occurrence and Localization in Various Animal Cells

DNA-dependent RNA-polymerase C, initially shown to exist in rat liver tissue and characterized by its sensitivity toward high concentrations of α-amanitin, has been shown to exist in HeLa cells and to be present in variable amounts in the nucleus of the rat liver cell. Enzyme C has been shown to co-chromatograph with nucleolar RNA polymerase A (or I) on DEAE-cellulose and can clearly be separated from the latter by chromatography on DEAE-Sephadex. It is possible that RNA polymerase C may occur in multiple forms although the significance of this finding is unclear at present. From its similar chromatographic properties and sensitivity toward α-amanitin it is possible that RNA polymerase C corresponds to polymerase III.