Abstract A procedure is described for the purification of DNA-dependent RNA polymerase II of the human tissue culture cell lines HeLa and KB. The enzyme has a molecular weight of approximately 500,000 and in sodium dodecyl sulfate polyacrylamide gels invariably shows 3 subunits with molecular weights of 220,000, 140,000, and 35,000. In addition there perhaps is a fourth subunit of about 25,000 daltons or less in mass and a subunit of 170,000 daltons occurring in variable amounts. RNA polymerase II has a strong preference for single-stranded over double-stranded DNA as template and is most active in the presence of 1.5 to 3 mm Mn++ as divalent cation. We also describe the partial purification of two stimulatory factors (SF-A and SF-B) which specifically stimulate the activity of RNA polymerase II in the presence of double-stranded DNA as template.
Sugden et al. (Fri,) studied this question.