Purification, cloning, and characterization of a human coactivator, PC4, that mediates transcriptional activation of class II genes

Cell. 1994 Aug 12;78(3):513-23. doi: 10.1016/0092-8674(94)90428-6.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Cloning, Molecular
  • DNA, Complementary / genetics
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / isolation & purification
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation*
  • HeLa Cells
  • Humans
  • Membrane Proteins / genetics*
  • Membrane Proteins / isolation & purification
  • Membrane Proteins / metabolism
  • Models, Genetic
  • Molecular Sequence Data
  • Protein Binding
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Sequence Homology, Amino Acid
  • Transcription Factor TFIIA
  • Transcription Factors / genetics*
  • Transcription Factors / isolation & purification
  • Transcription Factors / metabolism
  • Transcription, Genetic*


  • DNA, Complementary
  • DNA-Binding Proteins
  • GAL4 protein, S cerevisiae
  • Membrane Proteins
  • Recombinant Proteins
  • SUB1 protein, human
  • Saccharomyces cerevisiae Proteins
  • Transcription Factor TFIIA
  • Transcription Factors

Associated data

  • GENBANK/U12979