title: Phosphorylation and activation of the DNA binding activity of purified Stat1 by the Janus protein-tyrosine kinases and the epidermal growth factor receptor.
abstract: The activation of Janus protein-tyrosine kinases (Jaks) and the subsequent phosphorylation and activation of latent signal transducers and activators of transcription (Stats) are common elements in signal transduction through the cytokine receptor superfamily. To assess the role and specificity of Jaks in Stat activation, we have utilized baculovirus expression systems to produce Stat1 and the Jaks. Co-expression of Stat1 with Tyk2, Jak1, or Jak2 resulted in the specific tyrosine phosphorylation of Stat1 at Tyr701, the residue phosphorylated in mammalian cells stimulated with interferon gamma. Alternatively, Stat1, purified to apparent homogeneity from insect cell extracts, was phosphorylated at Tyr701 in Jak immune complex kinase reactions. Phosphorylation of purified Stat1 was necessary and sufficient for the acquisition of DNA binding activity. The specificity in both systems was indicated by the inability of a Jak2 catalytically inactive mutant (Jak2-Glu882) or the Tec protein-tyrosine kinase to phosphorylate Stat1. However, immune complex-purified epidermal growth factor receptor was capable of phosphorylating purified Stat1 at Tyr701 and activating its DNA binding activity in in vitro reactions.
authors.affiliation: Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: F W
authors.initials: FW
authors.lastname: Quelle
authors.forename: W
authors.initials: W
authors.lastname: Thierfelder
authors.forename: B A
authors.initials: BA
authors.lastname: Witthuhn
authors.forename: B
authors.initials: B
authors.lastname: Tang
authors.forename: S
authors.initials: S
authors.lastname: Cohen
authors.forename: J N
authors.initials: JN
authors.lastname: Ihle
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D008322:Mammals; D051379:Mice; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D010766:Phosphorylation; D014176:Protein Biosynthesis; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D050794:STAT1 Transcription Factor; D017386:Sequence Homology, Amino Acid; D012756:Sheep; D018411:Spodoptera; D053634:TYK2 Kinase; D015534:Trans-Activators / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D014162:Transfection; D014443:Tyrosine
chemical_list: D004268:DNA-Binding Proteins; D010748:Phosphopeptides; D011506:Proteins; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; C494080:Stat1 protein, mouse; D015534:Trans-Activators; D014443:Tyrosine; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; C507904:JAK1 protein, human; C507924:JAK2 protein, human; C507905:Jak1 protein, mouse; C507926:Jak2 protein, mouse; D053613:Janus Kinase 1; D053614:Janus Kinase 2; D053634:TYK2 Kinase; C070139:TYK2 protein, human; C499356:Tyk2 protein, mouse