Purification, analysis, and subunits of myeloma (MOPC 21) DNA-dependent RNA polymerase A (1) by...

DNA-dependent RNA polymerase A (or 1) was purified from murine myeloma MOPC 21 by diethylaminoethyl Sephadex chromatography. Further separation from DNA polymerases, protein kinase and DNA endonuclease was accomplished by polyriboadenylate-Sepharose affinity chromatography followed by gradient centrifugation. Yields following chromatography were 100%, but following gradient centrifugation only 25 to 30% of the activity remained. Addition of low-molecular-weight components increased yields to 50 to 60%. Several species of myeloma polymerase A could be detected, and subunits of 190,000 and 125,000 daltons were identified. No evidence of phosphorylation of the polymerase was found.