Abstract
The yeast protein Xtc1 was identified as a protein that binds directly and specifically to the activation domains of acidic activators such as E2F-1, Gal4 and VP16. Additionally, it was shown to co-purify with the RNA polymerase II holoenzyme complex and it was suggested that Xtc1 functions as a regulator of transcription that modulates the response of RNA polymerase II to transcriptional activators. We have further analyzed the transcription function of Xtc1 and show that its fusion to a heterologous DNA binding domain can repress transcription of a reporter gene in vivo in an Srb10/11-dependent manner. We suggest that the presence of Xtc1 in the RNA polymerase II holoenzyme could help to recruit an Srb10-active form of the holoenzyme to target promoters. This same protein has also been implicated in mitochondrial DNA recombination, maintenance and repair. Determination of the subcellular localization using a GFP-Xtc1 fusion shows that it localizes to both the nucleus and the mitochondria in vivo, which is consistent with Xtc1 having a function in both cellular compartments.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Nucleus / chemistry
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Cell Nucleus / metabolism
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Cyclin-Dependent Kinase 8
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Cyclin-Dependent Kinases / genetics
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Cyclin-Dependent Kinases / metabolism
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Cyclins / genetics
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Cyclins / metabolism
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Gene Expression Regulation, Fungal*
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Genes, Reporter
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Holoenzymes / chemistry
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Holoenzymes / metabolism
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Mitochondria / chemistry
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Mitochondria / metabolism
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Nuclear Proteins*
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Promoter Regions, Genetic / genetics
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Protein Structure, Tertiary
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Protein Transport
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RNA Polymerase II / chemistry
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RNA Polymerase II / metabolism
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Repressor Proteins / chemistry
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Repressor Proteins / genetics
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Repressor Proteins / 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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Saccharomyces cerevisiae* / cytology
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Saccharomyces cerevisiae* / enzymology
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Saccharomyces cerevisiae* / genetics
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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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Transcription, Genetic*
Substances
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Cyclins
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Holoenzymes
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MHR1 protein, S cerevisiae
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Nuclear Proteins
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Repressor Proteins
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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SSN8 protein, S cerevisiae
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Cyclin-Dependent Kinase 8
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Cyclin-Dependent Kinases
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SSN3 protein, S cerevisiae
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RNA Polymerase II