Signal transducer and transcription activator that mediates cellular responses to interferons (IFNs), cytokine KITLG/SCF and other cytokines and other growth factors. Following type I IFN (IFN-alpha and IFN-beta) binding to cell surface receptors, signaling via protein kinases leads to activation of Jak kinases (TYK2 and JAK1) and to tyrosine phosphorylation of STAT1 and STAT2. The phosphorylated STATs dimerize, associate with ISGF3G/IRF-9 to form a complex termed ISGF3 transcription factor, that enters the nucleus. ISGF3 binds to the IFN stimulated response element (ISRE) to activate the transcription of interferon stimulated genes, which drive the cell in an antiviral state. In response to type II IFN (IFN-gamma), STAT1 is tyrosine-and serine-phosphorylated. It then forms a homodimer termed IFN-gamma-activated factor (GAF), migrates into the nucleus and binds to the IFN gamma activated sequence (GAS) to drive the expression of the target genes, inducing a cellular antiviral state. Becomes activated in response to KITLG/SCF and KIT signaling. May mediate cellular responses to activated FGFR1, FGFR2, FGFR3 and FGFR4.
Specificity
Natural and recombinant Pig Signal transducer and activator of transcription 1
Subcellular Location
Cytoplasm Nucleus Translocated into the nucleus upon tyrosine phosphorylation and dimerization, in response to IFN-gamma and signaling by activated FGFR1; FGFR2; FGFR3 or FGFR4.
In response to IFN alpha/beta, three subunits (STAT1-alpha, STAT1-beta, STAT2) of ISGF3, become phosphorylated on tyrosine, migrate into the nucleus, and assemble into a complex together with ISGF3 gamma (p48), a DNA-binding protein that specifically binds to the IFN-stimulated response element. In response to IFN gamma, STAT1 forms homodimers, that also translocate into the nucleus to activate IFN gamma-responsive genes. Interacts with NMI. Interacts with PIAS1; the interaction requires phosphorylation on Ser-727 and inhibits STAT1 activation. Interacts with PIAS1 (dimethylated on arginine); the interaction results in release of STAT1 from its target gene. Interacts with IFNAR1; the interaction requires the phosphorylation of IFNAR1 at 'Tyr-467'. Interacts with IFNAR2.