PROSITE documentation PDOC00624
Transcription factor TFIIB repeat signature


In eukaryotes the initiation of transcription of protein encoding genes by polymerase II is modulated by general and specific transcription factors. The general transcription factors operate through common promoters elements (such as the TATA box). At least seven different proteins associates to form the general transcription factors: TFIIA, -IIB, -IID, -IIE, -IIF, -IIG, and -IIH [1].

Transcription factor IIB (TFIIB) plays a central role in the transcription of class II genes, it associates with a complex of TFIID-IIA bound to DNA (DA complex) to form a ternary complex TFIID-IIA-IBB (DAB complex) which is then recognized by RNA polymerase II [2,3]. TFIIB is a protein of about 315 to 340 amino acid residues which contains, in its C-terminal part an imperfect repeat of a domain of about 75 residues. This repeat could contribute an element of symmetry to the folded protein.

The following proteins have been shown to be evolutionary related to TFIIB:

  • An archaebacterial TFIIB homolog. In Pyrococcus woesei a previously undetected open reading frame has been shown [4] to be highly related to TFIIB.
  • Fungal transcription factor IIIB 70 Kd subunit (gene PCF4/TDS4/BRF1) [5]. This protein is a general activator of RNA polymerase III transcription and plays a role analogous to that of TFIIB in pol III transcription.

As a signature pattern we selected the central section of the repeated domain, which is the most conserved part of that domain.

Expert(s) to contact by email:

Ouzounis C.

Last update:

April 2006 / Pattern revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

TFIIB, PS00782; Transcription factor TFIIB repeat signature  (PATTERN)


1AuthorsWeinmann R.
TitleThe basic RNA polymerase II transcriptional machinery.
SourceGene Expr. 2:81-91(1992).
PubMed ID1633439

2AuthorsHawley D.
TitleTranscriptional activation: enter TFIIB.
SourceTrends Biochem. Sci. 16:317-318(1991).
PubMed ID1949150

3AuthorsHa I. Lane W.S. Reinberg D.
TitleCloning of a human gene encoding the general transcription initiation factor IIB.
SourceNature 352:689-695(1991).
PubMed ID1876184

4AuthorsOuzounis C. Sander C.
TitleTFIIB, an evolutionary link between the transcription machineries of archaebacteria and eukaryotes.
SourceCell 71:189-190(1992).
PubMed ID1423586

5AuthorsKhoo B. Brophy B. Jackson S.P.
TitleConserved functional domains of the RNA polymerase III general transcription factor BRF.
SourceGenes Dev. 8:2879-2890(1994).
PubMed ID7995525

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