The USA-derived transcriptional coactivator PC2 is a submodule of TRAP/SMCC and acts synergistically with other PCs

Mol Cell. 2000 Apr;5(4):753-60. doi: 10.1016/s1097-2765(00)80254-3.


PC2, the high-molecular weight constituent of the potent USA transcriptional coactivator fraction, was identified as a Mediator-like complex. Its composition resembles that of the TRAP/SMCC complex, but PC2 is distinguished by the prominent absence of the SRB10 and SRB11 kinase/cyclin pair, as well as several additional polypeptides. Furthermore, affinity-purified PC2, which lacks independent activity, acts in synergy with USA-derived coactivators PC3/topoisomerase I and PC4 to mediate the effects of a variety of activators (including VP16, the synthetic activator GAL4-AH, and the orphan nuclear receptor HNF4) and thus recapitulates partial USA coactivator function.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • HeLa Cells
  • Humans
  • Mediator Complex
  • Subcellular Fractions / chemistry
  • Trans-Activators*
  • Transcription Factors / chemistry*
  • Transcription Factors / metabolism*
  • Transcriptional Activation*


  • MED27 protein, human
  • Mediator Complex
  • Trans-Activators
  • Transcription Factors