A CDNA-ENCODING RAP74, A GENERAL INITIATION-FACTOR FOR TRANSCRIPTION BY RNA POLYMERASE-II

RAP30/74 (also known as TFIIF (refs 1, 2), beta-gamma (ref. 3) and FC (ref. 4)) is one of several general factors required for initiation by RNA polymerase II (reviewed in refs 5-7). The small RAP30 subunit of RAP30/74 binds directly to polymerase and appears structurally and functionally homologous to bacterial sigma factors in their RNA polymerase-binding region 8-10. RAP30/74 or recombinant RAP30 suppresses nonspecific binding of RNA polymerase II to DNA (refs 10, 11) and is required for RNA polymerase II to assemble stably into a preinitiation complex containing promoter DNA and the general factors TFIID, TFIIA and TFIIB (refs 2, 12, 13); both RAP30 and RAP74 are physical components of the preinitiation complex 2. A complementary DNA encoding human RAP30 has been isolated 8, and here we report the isolation of a cDNA encoding human RAP74. RAP30 and RAP74 produced in Escherichia coli can be used in place of natural human RAP30/74 to direct accurate transcription initiation by RNA polymerase II in vitro.