Purification, cloning, and characterization of a human coactivator, PC4, that mediates transcriptional activation of class II genes.
Activator-dependent transcription in mammalian cells requires upstream stimulatory activity (USA)-derived cofactors in addition to those present in TFIID. A novel positive cofactor (PC4) purified from the human USA fraction effected a marked enhancement (up to 85-fold) of GAL4-AH-dependent transcription in conjunction with TFIID and other general factors. Isolation of a corresponding cDNA identified PC4 as a 127 residue single-stranded DNA-binding protein with serine-rich regions near the N-terminus. Recombinant PC4 was functionally equivalent to native PC4, and both proteins markedly enhanced activation by diverse activation domains fused to the DNA-binding domain of GAL4. Recombinant PC4 interacted independently both with free or DNA-bound VP16 activation domains and with free or DNA-bound TFIIA-TBP complexes (but not with TBP alone). These results indicate that PC4 is a general coactivator that functions cooperatively with TAFs and mediates functional interactions between upstream activators and the general transcriptional machinery.
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Laboratory of Biochemistry and Molecular Biology, Rockefeller University.
Roeder
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D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D005786:Gene Expression Regulation; D006367:HeLa Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011485:Protein Binding; D011994:Recombinant Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D035561:Transcription Factor TFIIA; D014157:Transcription Factors / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D014158:Transcription, Genetic
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C052130:GAL4 protein, S cerevisiae; D008565:Membrane Proteins; D011994:Recombinant Proteins; C509201:SUB1 protein, human; D029701:Saccharomyces cerevisiae Proteins; D035561:Transcription Factor TFIIA; D014157:Transcription Factors