Mechanism of transcriptional activation by Sp1: evidence for coactivators.
In reconstituted reactions, Sp1 stimulates transcription at TATA-containing promoters in the presence of semipurified TFIID fractions from either human or Drosophila cells, but is unable to do so when these fractions are replaced by purified, cloned Drosophila or yeast TFIID. Our findings with Sp1 and CTF suggest that partially purified TFIID fractions from human and Drosophila cells contain coactivators that are dispensable for basal transcription but are required as molecular adaptors between trans-activators and the general transcription initiation machinery. Experiments using cloned TFIID proteins suggest that these coactivators function through the amino-terminal portion of TFIID and that coactivator-TFIID interactions are species specific. At promoters lacking a TATA box, an additional activity distinct from coactivators is required for Sp1 activation of transcription.
Howard Hughes Medical Institute, Department of Molecular and Cell Biology, University of California, Berkeley 94720.
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D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D008957:Models, Genetic; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016329:Sp1 Transcription Factor; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D015345:Oligonucleotide Probes; D011994:Recombinant Proteins; D016329:Sp1 Transcription Factor; D035362:Transcription Factor TFIID; D014157:Transcription Factors