title: Activation of transcription by IFN-gamma: tyrosine phosphorylation of a 91-kD DNA binding protein.
abstract: Interferon-gamma (IFN-gamma) induces the transcription of the gene encoding a guanylate binding protein by activating a latent cytoplasmic factor, GAF (gamma-activated factor). GAF is translocated to the nucleus and binds a DNA element, the gamma-activated site. Through cross-linking and the use of specific antibodies GAF was found to be a 91-kilodalton DNA binding protein that was previously identified as one of four proteins in interferon-stimulated gene factor-3 (ISGF-3), a transcription complex activated by IFN-alpha. The IFN-gamma-dependent activation of the 91-kilodalton DNA binding protein required cytoplasmic phosphorylation of the protein on tyrosine. The 113-kilodalton ISGF-3 protein that is phosphorylated in response to IFN-alpha was not phosphorylated nor translocated to the nucleus in response to IFN-gamma. Thus the two different ligands result in tyrosine phosphorylation of different combinations of latent cytoplasmic transcription factors that then act at different DNA binding sites.
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D016898:Interferon-alpha / Q000494:pharmacology; D007371:Interferon-gamma / Q000494:pharmacology*; D008954:Models, Biological; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides; D010766:Phosphorylation; D019000:Phosphotyrosine; D011401:Promoter Regions, Genetic; D050794:STAT1 Transcription Factor; D015398:Signal Transduction / Q000187:drug effects; D015534:Trans-Activators; D014158:Transcription, Genetic / Q000187:drug effects; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis
chemical_list: D004268:DNA-Binding Proteins; D016898:Interferon-alpha; D009838:Oligodeoxyribonucleotides; D050794:STAT1 Transcription Factor; D015534:Trans-Activators; D019000:Phosphotyrosine; D014443:Tyrosine; D007371:Interferon-gamma; D019204:GTP-Binding Proteins