Basal transcription factors

Basal transcription factors - TBP-associated factors ( TAF...

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Basal transcription factors There at least 5 basal transcription factors, [ still under investigation] (TFIIB, TFIID, TFIIE, TFIIF, TFIIH): TF indicates transcription factor, II indicates specificity for polymerase II) Sequence comparisons of RNA polymerase II promoters have revealed: a consensus sequence of TATAA at -25 to -30 , called TATA box (note similarity to -10 sequence or TATAAT in prokaryotes) A protein called TATA-binding protein ( TBP ) binds specifically to the TATA box. TBP is part of a large protein complex called TFIID that also contains other polypeptides called
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Unformatted text preview: TBP-associated factors ( TAF s) Transcription is initiated by TFIID specifically binding to the TATA box via its TBP subunit (see figure in text) The TBP subunit can then bind another transcription factor called TFIIB forming a TBP-TFIIB complex Only now can RNA polymerase II bind to the promoter via binding to the TBP-TFIIB complex. However, it does so only in association with a third transcription factor called TFIIF . Before transcription can really be initiated in vitro , 2 other transcription factors must bind to RNA polymerase II: TFIIE and TFIIH ....
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