Abstract
In yeast, SPT3 is a component of the multiprotein SPT-ADA-GCN5 acetyltransferase (SAGA) complex that integrates proteins with transcription coactivator/adaptor functions (ADAs and GCN5), histone acetyltransferase activity (GCN5), and core promoter-selective functions (SPTs) involving interactions with the TATA-binding protein (TBP). In particular, yeast SPT3 has been shown to interact directly with TBP. Here we report the molecular cloning of a cDNA encoding a human homologue of yeast SPT3. Amino acid sequence comparisons between human SPT3 (hSPT3) and its counterparts in different yeast species reveal three highly conserved domains, with the most conserved 92-amino acid N-terminal domain being 25% identical with human TAFII18. Despite the significant sequence similarity with TAFII18, native hSPT3 is not a bona fide TAFII because it is not associated in vivo either with human TBP/TFIID or with a TFIID-related TBP-free TAFII complex. However, we present evidence that hSPT3 is associated in vivo with TAFII31 and the recently described longer form of human GCN5 (hGCN5-L) in a novel human complex that has histone acetyltransferase activity. We propose that the human SPT3-TAFII31-GCN5-L acetyltransferase (STAGA) complex is a likely homologue of the yeast SAGA complex.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Acetyltransferases / chemistry
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Acetyltransferases / genetics
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Acetyltransferases / metabolism*
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Amino Acid Sequence
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Base Sequence
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Carrier Proteins / chemistry
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Carrier Proteins / genetics*
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Carrier Proteins / metabolism*
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Cell Cycle Proteins
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Cloning, Molecular
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Conserved Sequence
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DNA-Binding Proteins / metabolism*
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HeLa Cells
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Histone Acetyltransferases
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Humans
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Molecular Sequence Data
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Recombinant Proteins / metabolism
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins*
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Sequence Alignment
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Sequence Homology, Amino Acid
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TATA-Binding Protein Associated Factors*
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Trans-Activators / chemistry
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Trans-Activators / genetics*
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Trans-Activators / metabolism*
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Transcription Factor TFIID
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Transcription Factors / metabolism*
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Transcription Factors, TFII / metabolism*
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p300-CBP Transcription Factors
Substances
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Carrier Proteins
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Cell Cycle Proteins
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DNA-Binding Proteins
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Recombinant Proteins
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SUPT3H protein, human
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Saccharomyces cerevisiae Proteins
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TAF9 protein, human
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TATA-Binding Protein Associated Factors
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Trans-Activators
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Transcription Factor TFIID
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Transcription Factors
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Transcription Factors, TFII
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Acetyltransferases
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Histone Acetyltransferases
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KAT2A protein, human
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p300-CBP Transcription Factors
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p300-CBP-associated factor