Chapter category: Gene Expression
Class III Genes
RNA Polymerase III Transcription
Second Edition
Edited by: Robert J. WhiteISBN: 1-57059-482-1
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Chapter authors:
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 for protein synthesis, 7SL RNA, which is involved in intracellular protein transport, and the U6, H1 and MRP RNAs, which are involved in posttranscriptional processing. The VA RNAs encoded by adenovirus are also synthesized by pol III, and these serve to divert the translational machinery of an infected cell towards the more effective production of viral proteins. Other class III genes encode transcripts with no known function. This category includes the 7SK genes and the short interspersed repeat (SINE) gene families which constitute the majority of class III templates in mammals. The aim of this Chapter is to describe these various gene families, which are the DNA templates for pol III transcription. Table 2 lists the class III genes found in the draft human genome sequence, as well as the many pseudogenes derived from them.1 Indeed, pol III templates generally provide the most prolific sources of pseudogenes.
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
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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
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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 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 ...
