Recombinant TBP, transcription factor IIB, and RAP30 are sufficient for promoter recognition by mammalian RNA polymerase II.

Initiation of transcription by RNA polymerase II is a complex, multistep process which requires several accessory factors in addition to the polymerase itself. A critical event in transcription initiation is the specific association of RNA polymerase II with promoter DNA. In this report we show that three eukaryotic polypeptides, produced in Escherichia coli and purified to near homogeneity, constitute a minimal set of general transcription factors both necessary and sufficient for specific and stable promoter binding by RNA polymerase II. These polypeptides are the yeast TATA box binding protein TBP, the human general initiation factor TFIIB, and human RAP30, the small subunit of RAP30/74 (or transcription factor IIF). Formation of the polymerase-containing complex required only the TATA box, and not the initiator element (Inr), of the adenovirus major late promoter which was used in these experiments.