PROSITE documentation PDOC00624Transcription 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: Last update:April 2006 / Pattern revised.
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PROSITE method (with tools and information) covered by this documentation:
| 1 | Authors | Weinmann R. |
| Title | The basic RNA polymerase II transcriptional machinery. | |
| Source | Gene Expr. 2:81-91(1992). | |
| PubMed ID | 1633439 |
| 2 | Authors | Hawley D. |
| Title | Transcriptional activation: enter TFIIB. | |
| Source | Trends Biochem. Sci. 16:317-318(1991). | |
| PubMed ID | 1949150 |
| 3 | Authors | Ha I. Lane W.S. Reinberg D. |
| Title | Cloning of a human gene encoding the general transcription initiation factor IIB. | |
| Source | Nature 352:689-695(1991). | |
| PubMed ID | 1876184 | |
| DOI | 10.1038/352689a0 |
| 4 | Authors | Ouzounis C. Sander C. |
| Title | TFIIB, an evolutionary link between the transcription machineries of archaebacteria and eukaryotes. | |
| Source | Cell 71:189-190(1992). | |
| PubMed ID | 1423586 |
| 5 | Authors | Khoo B. Brophy B. Jackson S.P. |
| Title | Conserved functional domains of the RNA polymerase III general transcription factor BRF. | |
| Source | Genes Dev. 8:2879-2890(1994). | |
| PubMed ID | 7995525 |
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