TFIIB

Image of TFIIB adopted from http://www.biochem.ucl.ac.uk/bsm/xtal/teach/trans/tata.html

TFIIB is thought to be the third complex to interact with the DNA promoter region. A small protein, it contains only one subunit about 35-40 kD in size. It contains a Zinc-finger domain at its N-terminus, where it binds to the DNA (Buratowski, 2001). It also binds directly to and stabilizes TBP binding to DNA by causing conformational changes in TFIID ’s binding cavity (Brody, 2001).
TFIIB’s position on the DNA was found using DNA footprinting, which indicated that it covers base pairs –80 to –17 and –10 to +10 (McClean, 1997). Using electron microscopy, the Lawrence Berkeley National Laboratory learned its position in relation to TFIID, TFIIA , and DNA in the complex (Yarris, 1999).
Through an interaction with TFIIF , TFIIB recruits RNA Polymerase II to the promoter site (Brody, 2001). TFIIB also may be a site where regulatory factors can bind to either enhance or block the initiation of transcription (Buratowski, 1999).

TFIIb front and side views adopted from http://tfiib.med.harvard.edu/transcription/tfiib.html

Click on the following links to view a specific transcription factor.
TFIIA , TFIIB , TFIID , TFIIE , TFIIF , TFIIH , TFII I , TFIIS

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