title: Components of a Stat recognition code: evidence for two layers of molecular selectivity.
abstract: Latent and activated forms of Stat1 and Stat6 have been expressed and purified, enabling biochemical experiments relating to their functional activities. Stat1 bound to a phosphotyrosine peptide derived from the IFN gamma receptor with a KD of 50 nM, whereas Stat6 bound to an IL-4 receptor peptide with a KD of 300 nM. Stat-receptor peptide interactions were specific and dependent upon tyrosine phosphorylation. Activated forms of Stat1 and Stat6 were used to select their optimal DNA binding sites. Stat1 selected a recognition site having dyad half-sites separated by 3 bp. Stat6 selected a recognition site composed of the same dyad half-sites, yet separated by 4 bp. Chimeric Stat1-Stat6 recombinants were expressed, purified, and assayed for receptor coupling and DNA binding specificity. Such studies led to the identification of polypeptide domains that specify these activities. These observations provide a framework for understanding how different cytokines elicit distinctive patterns of gene expression.
authors.affiliation: Tularik, Incorporated, South San Francisco, California 94080, USA.
authors.forename: U
authors.initials: U
authors.lastname: Schindler
authors.forename: P
authors.initials: P
authors.lastname: Wu
authors.forename: M
authors.initials: M
authors.lastname: Rothe
authors.forename: M
authors.initials: M
authors.lastname: Brasseur
authors.forename: S L
authors.initials: SL
authors.lastname: McKnight
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D005454:Fluorescence Polarization / Q000379:methods; D006801:Humans; D008969:Molecular Sequence Data; D010748:Phosphopeptides / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D050794:STAT1 Transcription Factor; D050800:STAT6 Transcription Factor; D015534:Trans-Activators / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D010748:Phosphopeptides; D011993:Recombinant Fusion Proteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D015534:Trans-Activators