General transcription factor

General transcription factors (GTF's) or basal transcription factors are protein transcription factors that have been shown to be important in the transcription of class II genes to mRNA templates cite journal | author = Lee TI, Young RA | title = Transcription of eukaryotic protein-coding genes | journal = Annu. Rev. Genet. | volume = 34 | issue = | pages = 77–137 | year = 2000 | pmid = 11092823 | doi = 10.1146/annurev.genet.34.1.77] . Many of them are involved in the formation of a preinitiation complex, which, together with RNA polymerase II, bind to and read the single-stranded DNA gene template.cite journal | author = Orphanides G, Lagrange T, Reinberg D | title = The general transcription factors of RNA polymerase II | journal = Genes Dev. | volume = 10 | issue = 21 | pages = 2657–83 | year = 1996 | pmid = 8946909 | doi = 10.1101/gad.10.21.2657 ]

Functions

GTFs are intimately involved in the process of gene regulation, and most are required for life. TATA binding protein, (TBP) is a GTF that binds to the TATAA box (T=Thymine, A=Adenine) the motif of nucleic acids that is directly upstream from the coding region in all genes. TBP is responsible for the recruitment of the RNA Pol II holoenzyme, the final event in transcription initiation. These proteins are ubiquitous and interact with the core promoter region of DNA, which contains the transcription start site(s) of all class II genes.

Not all GTFs play a role in transcriptional initiation; some are required for the second general step in transcription, elongation. For example, members of the FACT complex (Spt16/Pob3 in "S. cerevisiae", SUPT16H/SSRP1 in humans) facilitate the rapid movement of RNA Pol II over the encoding region of genes. This is accomplished by moving the histone octamer out of the way of an active polymerase and thereby decondensing the chromatin.

Types

The general transcription factors that are required for transcription by RNA polymerase II in a test tube arecite journal | author = Lee TI, Young RA | title = Transcription of eukaryotic protein-coding genes | journal = Annu. Rev. Genet. | volume = 34 | issue = | pages = 77–137 | year = 2000 | pmid = 11092823 | doi = 10.1146/annurev.genet.34.1.77] :
* [http://tfiib.med.harvard.edu/transcription/tfiia.html TFIIA] (see TFIIA; TFIIA is not a real basal transcription factor.)
* [http://tfiib.med.harvard.edu/transcription/tfiib.html TFIIB] (see TFIIB)
* [http://tfiib.med.harvard.edu/transcription/tfiid.html TFIID] (see TFIID and TATA binding protein)
* [http://tfiib.med.harvard.edu/transcription/tfiie.html TFIIE] (see TFIIE)
* [http://tfiib.med.harvard.edu/transcription/tfiif.html TFIIF] (see TFIIF)
* [http://tfiib.med.harvard.edu/transcription/tfiih.html TFIIH] (see TFIIH)

Note: Basal transcription in test tubes has been achieved using only highly-purified recombinant TFIIB and TFIIF.

See also

* RNA polymerase II for simpler explanation on transcription factors
* Nuclear receptor, an important class of transcription factors

References

External links

* http://www.yeastgenome.org has highly detailed information on most known GTF's and is an excellent resource for students and researchers alike
*
*Descriptive images of GTF assembly
** [http://www.bmb.psu.edu/nixon/bmb400/Image5.gifbmb.psu.edu]
** [http://www.imcb.osaka-u.ac.jp/en/seminar/image/04_img1.jpgimcb.osaka-u.ac.jp]
** [http://www.biochem.ucl.ac.uk/bsm/xtal/teach/trans/pol2.gifbiochem.ucl.ac.uk]