Transcription Factor H
TFIIH is composed of 9 - 10 subunits and can be divided into 2 parts, the Core and the Cak. Located in the Core is XPB and XPD helicase subunits with are orthologs of yeast Ss12 and Rad3 , XPB promotes DNA unwinding which is need for the RNA to successfully transcribe the DNA to mRNA. This step is energy dependent so requires hydrolysis of ATP. The Cak region has kinases which phosphorylates a serine in the fifth position of the cysteine rich domain of RNA polymerase 2, this step is essential as it causes a conformational change to tighten its interaction with the DNA and leave some of the transcription factors behind. Cak can also dissociate away from TFIIH as it has other roles in cell cycle regulation.
Some diseases associated with TFIIH mutations include:
- ↑ Goel Shivani, Krishnamurthy Shankarling, Hampsey Michael (2011) The mechanism of start site selection by RNA polymerase II: interplay between TFIIB and the Ssl2/XPB helicase subunit of TFIIH; J Biol Chem; [Epub ahead of print]
- ↑ Alberts et al. (2008) Molecular biology of the cell, 5th edition,pages;341 . garland science,madison avenue,new york.
- ↑ Alberts et al. (2008) Molecular biology of the cell, 5th edition,pages;341, 342 . garland science,madison avenue,new york.