Factors involved in specific transcription by mammalian RNA polymerase II. RNA polymerase II-associating protein 30 is an essential component of transcription factor IIF

Abstract

Transcription from class II promoters requires five general factors, IIA, IIB, IID, IIE, and IIF, in addition to RNA polymerase II for basal levels of transcription (Reinberg, D., Flores, O., and Buckbinder, L. (1987) in Molecular Biology of RNA: New Perspectives (Inouye, M., and Dudock, B., eds) pp. 423-439, Academic Press, Orlando, FL). A protein fraction containing transcription factors (TF) IIE and IIF was able to reconstitute transcription from the adenovirus major late promoter when added to extracts depleted of the RNA polymerase II-associating proteins RAP 30 and RAP 74 (Sopta, M., Carthew, R.W., and Greenblatt, J. (1985) J. Biol. Chem. 260, 10353-10360). Studies with monoaffinity-purified antibodies directed against RAP 30 demonstrated, by Western blot analysis, that RAP 30 copurifies on five columns with transcription factor IIF. That RAP 30 is a functional component of TFIIF was also demonstrated; preincubation of anti-RAP 30 antibodies with purified TFIIF inhibited transcription. Inhibition of transcription was overcome by the addition of purified TFIIF. RAP 30 is an integral part of a preinitiation complex; the incubation of all the general transcription factors with a promoter-containing DNA, prior to the addition of the anti-RAP 30 antibodies, resulted in the formation of a DNA-protein complex that was not inhibited by the antibodies. Incubation of the transcription factors in the absence of a promoter-containing DNA resulted in a complex that was partially resistant to the antibodies.