Human p32, interacts with B subunit of the CCAAT-binding factor, CBF/NF-Y, and inhibits CBF-mediated transcription activation in vitro

Nucleic Acids Res. 2004 Jul 8;32(12):3632-41. doi: 10.1093/nar/gkh692. Print 2004.


To understand the role of the CCAAT-binding factor, CBF, in transcription, we developed a strategy to purify the heterotrimeric CBF complex from HeLa cell extracts using two successive immunoaffinity chromatography steps. Here we show that the p32 protein, previously identified as the ASF/SF2 splicing factor-associated protein, copurified with the CBF complex. Studies of protein-protein interaction demonstrated that p32 interacts specifically with CBF-B subunit and also associates with CBF-DNA complex. Cellular localization by immunofluorescence staining revealed that p32 is present in the cell throughout the cytosol and nucleus, whereas CBF is present primarily in the nucleus. A portion of the p32 colocalizes with CBF-B in the nucleus. Interestingly, reconstitution of p32 in an in vitro transcription reaction demonstrated that p32 specifically inhibits CBF-mediated transcription activation. Altogether, our study identified p32 as a novel and specific corepressor of CBF-mediated transcription activation in vitro.

Publication types

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

MeSH terms

  • CCAAT-Binding Factor / analysis
  • CCAAT-Binding Factor / antagonists & inhibitors*
  • CCAAT-Binding Factor / metabolism
  • Carrier Proteins
  • Cell Nucleus / chemistry
  • Chromatography, Affinity
  • HeLa Cells
  • Humans
  • Hyaluronan Receptors*
  • Macromolecular Substances
  • Membrane Glycoproteins*
  • Mitochondrial Proteins
  • Protein Subunits / metabolism
  • Receptors, Complement / analysis
  • Receptors, Complement / metabolism
  • Receptors, Complement / physiology*
  • Recombinant Proteins / metabolism
  • Repressor Proteins / analysis
  • Repressor Proteins / metabolism
  • Repressor Proteins / physiology*
  • Transcriptional Activation*


  • C1QBP protein, human
  • CCAAT-Binding Factor
  • Carrier Proteins
  • Hyaluronan Receptors
  • Macromolecular Substances
  • Membrane Glycoproteins
  • Mitochondrial Proteins
  • Protein Subunits
  • Receptors, Complement
  • Recombinant Proteins
  • Repressor Proteins
  • complement 1q receptor