Abstract
There is limited information on how eukaryotic RNA polymerases (Pol) recognize their cognate preinitiation complex. We have characterized a polypeptide copurifying with yeast Pol III. This protein, C17, was found to be homologous to a mammalian protein described as a hormone receptor. Deletion of the corresponding gene, RPC17, was lethal and its regulated extinction caused a selective defect in transcription of class III genes in vivo. Two-hybrid and coimmunoprecipitation experiments indicated that C17 interacts with two Pol III subunits, one of which, C31, is important for the initiation reaction. C17 also interacted with TFIIIB70, the TFIIB-related component of TFIIIB. The interaction domain was found to be in the N-terminal, TFIIB-like half of TFIIIB70, downstream of the zinc ribbon and first imperfect repeat. Although Pol II similarly interacts with TFIIB, it is notable that C17 has no similarity to any Pol II subunit. The data indicate that C17 is a novel specific subunit of Pol III which participates together with C34 in the recruitment of Pol III by the preinitiation complex.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Binding Sites
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Cloning, Molecular
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Conserved Sequence / genetics
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Fungal Proteins / chemistry
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Fungal Proteins / genetics
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Fungal Proteins / metabolism
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Genes, Essential / genetics
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Humans
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Molecular Sequence Data
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Molecular Weight
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Mutation / genetics
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Open Reading Frames / genetics
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Peptide Fragments / chemistry
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Peptide Fragments / genetics
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Peptide Fragments / metabolism
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Precipitin Tests
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Protein Binding
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RNA Polymerase III / chemistry*
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RNA Polymerase III / genetics
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RNA Polymerase III / metabolism*
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Saccharomyces cerevisiae / enzymology
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / growth & development
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Saccharomyces cerevisiae / metabolism*
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Saccharomyces cerevisiae Proteins / chemistry*
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Saccharomyces cerevisiae Proteins / genetics
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Saccharomyces cerevisiae Proteins / metabolism*
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Sequence Alignment
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Transcription Factor TFIIIB
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Transcription Factors / chemistry*
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Two-Hybrid System Techniques
Substances
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Fungal Proteins
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Peptide Fragments
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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Transcription Factor TFIIIB
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Transcription Factors
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C17 protein, S cerevisiae
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RNA Polymerase III