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COMMENTARY |
1
National Institutes of Health, National Institute of Child Health and Human
Development, Cell Biology and Metabolism Branch, Building 18T, Room 101,
Bethesda, MD 20892, USA
2
Zentrum fur Molekulare Biologie der Universtät
Heidelberg (ZMBH), Im Neunheimer Feld 282, Heidelberg 69120, Germany
*
Author for correspondence (e-mail:
f.sauer{at}mail.zmbh.uni-heidelberg.de
)
Activation of RNA-polymerase-II-dependent transcription involves conversion of signals provided by gene-specific activator proteins into the synthesis of messenger RNA. This conversion requires dynamic structural changes in chromatin and assembly of general transcription factors (GTFs) and RNA polymerase II at core promoter sequence elements surrounding the transcription start site of genes. One hallmark of transcriptional activation is the interaction of DNA-bound activators with coactivators such as the TATA-box binding protein (TBP)-associated factors (TAFIIs) within the GTF TFIID. TAFII250 possesses a variety of activities that are likely to contribute to the initial steps of RNA polymerase II transcription. TAFII250 is a scaffold for assembly of other TAFIIs and TBP into TFIID, TAFII250 binds activators to recruit TFIID to particular promoters, TAFII250 regulates binding of TBP to DNA, TAFII250 binds core promoter initiator elements, TAFII250 binds acetylated lysine residues in core histones, and TAFII250 possesses protein kinase, ubiquitin-activating/conjugating and acetylase activities that modify histones and GTFs. We speculate that these activities achieve two goals - (1) they aid in positioning and stabilizing TFIID at particular promoters, and (2) they alter chromatin structure at the promoter to allow assembly of GTFs - and we propose a model for how TAFII250 converts activation signals into active transcription.
Key words: TAFII250, TFIID, Histone acetyltransferase, Kinase, Ubiquitination, Chromatin, Transcription
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