Chapter category: Gene Expression
RNA Polymerase III
RNA Polymerase III Transcription
Second Edition
Edited by: Robert J. WhiteISBN: 1-57059-482-1
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Chapter authors:
Robert J. White
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Pol III is the largest of the nuclear RNA polymerases, with an aggregate molecular weight of 600700 kD (reviewed by Thuriaux and Sentenac1–3). This is, perhaps, surprising since pol II transcribes a much larger and more diverse set of templates, and so might have been expected to show the greatest complexity. However, several transcription factors have been described that bind tightly and specifically to pol II.4–6 These include TFIIF, which is involved in recruiting pol II to initiation complexes, reducing its binding to nonspecific sites, and suppressing pausing during elongation.7,8 It has been found that TFIIF is not required for VAI transcription.9 Its function in the class III system, and those of the other pol II-associated factors, may possibly be performed by the additional subunits that copurify with pol III.
Additional chapters from this book:
Perspective
Robert J. White
Our understanding of the details of pol III transcription has increased substan-tially in recent years. The characterization and cloning of many of the components of the system have been ac...
Regulation of RNA Polymerase III Transcription
Robert J. White
There are two families of active 5S genes in Xenopus laevis. One consists of the somatic 5S genes, of which there are 400 copies per haploid genome, organized in a single cluster.
Proteins that Modulate the Rate of RNA Polymerase III Transcription
Robert J. White
So far I have described the basal pol III transcription apparatus and how this functions to allow expression of class III genes. The level of transcription can be modulated in either a posi...
Chromatin Structure of Class III Genes
Robert J. White
The chromatin structure of a gene can be a major determinant of its transcrip-tional activity (reviewed in refs. 1–8). In chromatin, 146 bp of DNA is wrapped approximately twice around...
Transcription
Robert J. White
Once a preinitiation complex has formed on a yeast tRNA gene, RNA chain ini-tiation requires a further 5 min at 22°C (half-life ~2 min).1 During this period, three successiv...
Transcription Complex Formation on Class III Genes
Robert J. White
The formation of transcription complexes, composed of factors bound to DNA, was initially investigated by means of the template exclusion assay. This approach monitors the ability of a gene...
Transcription Factors Utilized by RNA Polymerase III
Robert J. White
Purified pol III initiates transcription randomly.1–4 Accurate and specific initia-tion requires the assistance of transcription factors in order to recruit the polymerase t...
RNA Polymerase III
Robert J. White
Pol III is the largest of the nuclear RNA polymerases, with an aggregate molecular weight of 600700 kD (reviewed by Thuriaux and Sentenac1–3). This is, perhaps, surprising s...
Promoter Structure of Class III Genes
Robert J. White
The promoters of most class III genes include discontinuous intragenic structures, termed internal control regions (ICRs), that are composed of essential sequence blocks separated by noness...
Class III Genes
Robert J. White
The genes transcribed by pol III encode a variety of small RNA molecules. (Table 1) Many of these have essential functions in cellular metabolism, such as tRNA and 5S rRNA, which are required ...
