DNA Dependent RNA Polymerase from Ehrlich Ascites Tumor Cells

II. Factors Stimulating the Activity of RNA Polymerase II

Abstract

Two factors stimulating RNA polymerase II [EC 2. 7. 7. 6] of Ehrlich ascites tumor cells were isolated. Both factors showed significant template specificity. One of them, S-I, stimulated RNA synthesis on Ehrlich ascites tumor DNA, rat hepatoma DNA and poly dAT but not on DNA of calf thymus or Φ₈₀. The other factor, S-II, stimulated RNA synthesis only when Ehrlich ascites tumor DNA or rat hepatoma DNA was used as template and had no effect using poly dAT or calf thymus or Φ₈₀ DNA. Neither factor stimulated RNA synthesis by E. coli RNA polymerase on DNA of Ehrlich ascites tumor cells. Both factors were found to have affinity for Ehrlich ascites tumor DNA. These factors were effective when added in the initiation stage of transcription. When these factors were preincubated with DNA and then removed, their readdition to the DNA no longer stimulated RNA synthesis. The stimulatory activities of the two factors could not be separated from their ribonuclease H activities.