Identification and characterization of Ref-1, a nuclear protein that facilitates AP-1 DNA-binding activity

EMBO J. 1992 Feb;11(2):653-65.


Fos and Jun form a heterodimeric complex that regulates gene transcription by binding to the activator protein-1 (AP-1) DNA sequence motif. Previously, we demonstrated that the DNA-binding activity of Fos and Jun is regulated in vitro by a novel redox (reduction-oxidation) mechanism. Reduction of a conserved cysteine (cys) residue in the DNA-binding domains of Fos and Jun by chemical reducing agents or by a nuclear redox factor stimulates DNA-binding activity. Here, we describe purification and characterization of a 37 kDa protein (Ref-1) corresponding to the redox factor. Although Ref-1 does not bind to the AP-1 site in association with Fos and Jun, it partially copurifies with a subset of AP-1 proteins. Purified Ref-1 protein stimulates AP-1 DNA-binding activity through the conserved Cys residues in Fos and Jun, but it does not alter the DNA-binding specificity of Fos and Jun. Ref-1 may represent a novel redox component of the signal transduction processes that regulate eukaryotic gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Nucleus / metabolism
  • Chromatography, Affinity
  • Chromatography, Gel
  • DNA-Binding Proteins / metabolism*
  • Electrophoresis, Polyacrylamide Gel
  • HeLa Cells
  • Humans
  • Molecular Weight
  • Nuclear Proteins / isolation & purification
  • Nuclear Proteins / metabolism*
  • Oligodeoxyribonucleotides / metabolism*
  • Oxidation-Reduction
  • Proto-Oncogene Proteins c-fos / metabolism*
  • Proto-Oncogene Proteins c-jun / metabolism*
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae Proteins*
  • Signal Transduction
  • Trans-Activators*
  • Transcription Factors


  • DNA-Binding Proteins
  • HAP1 protein, S cerevisiae
  • Nuclear Proteins
  • Oligodeoxyribonucleotides
  • Proto-Oncogene Proteins c-fos
  • Proto-Oncogene Proteins c-jun
  • Recombinant Proteins
  • Saccharomyces cerevisiae Proteins
  • Trans-Activators
  • Transcription Factors