A Factor Stimulating the Transcription on Double-Stranded DNA by Purified RNA Polymerase from Rat Liver Nuclei

RNA polymerase (E.C.2.7.7.6.) of bacterial (Burgess et al., 1969; Bautz et al., 1969; Summers and Siegel, 1969) and other microbial sources (Losick and Sonensheim, 1969) has been shown to be an important element of positive control of transcription. In order to understand more clearly the complex mechanism of transcription in higher organisms, and to relate it to the known facts in microbial systems, RNA polymerase has been extracted and purified from a number of eucaryotic tissues. It has been found that multiple forms of the enzyme exist (Roeder and Rutter, 1969; Kedinger et al., 1970) and that the enzyme which is supposedly localized in the nucleoplasm (Roeder and Rutter, 1970; Jacob et al., 1970) utilizes denatured DNA more effectively than native DNA (Seifart, 1970; Roeder and Rutter, 1969; Stein and Hausen, 1969). This does not seem to be the case for more crude preparations from testicular and bovine lymphosarcoma tissue