Identification and characterization of Ref-1, a nuclear protein that facilitates AP-1 DNA-binding activity.
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.
Xanthoudakis
S
S
Department of Molecular Oncology and Virology, Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110.
Curran
T
T
D002467:Cell Nucleus / Q000378:metabolism; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells; D006801:Humans; D008970:Molecular Weight; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009838:Oligodeoxyribonucleotides / Q000378:metabolism*; D010084:Oxidation-Reduction; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D015398:Signal Transduction; D015534:Trans-Activators; D014157:Transcription Factors
D004268:DNA-Binding Proteins; C058452:HAP1 protein, S cerevisiae; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D014157:Transcription Factors