Cell Signaling Technology

Product Pathways - Jak/Stat Pathway

Phospho-Stat1 (Ser727) Antibody #9177

Applications Reactivity MW (kDa) Source
W IP IF-IC H M R 91 Rabbit

Applications Key:  W=Western Blotting  IP=Immunoprecipitation  IF-IC=Immunofluorescence (Immunocytochemistry)
Reactivity Key:  H=Human  M=Mouse  R=Rat
Species enclosed in parentheses are predicted to react based on 100% sequence homology. Species cross-reactivity is determined by Western blot.

Specificity / Sensitivity

Phospho-Stat1 (Ser727) Antibody detects endogenous levels of Stat1α only when phosphorylated at Ser727. This site is deleted in Stat1β. This antibody does not significantly cross-react with the corresponding phosphorylated residues of other Stat proteins.

Source / Purification

Polyclonal antibodies are produced by immunizing rabbits with a synthetic phosphopeptide (KLH-coupled) corresponding to residues surrounding Ser727 of human Stat1. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from 293 (human), NIH/3T3 (mouse), and C6 (rat) cells, untreated or UV-stimulated, using Phospho-Stat1 (Ser727) Antibody

IF-IC

IF-IC

Confocal immunofluorescent analysis of HeLa cells, untreated (left), IFN-γ treated (center) or IFN-γ and phosphatase treated (right), labeled with Phospho-Stat1 (Ser727) Antibody (green) and Pan-Keratin (C11) Mouse mAb #4545 (red).

Background

The Stat1 transcription factor is activated in response to a large number of ligands (1) and is essential for responsiveness to IFN-α and IFN-γ (2,3). Phosphorylation of Stat1 at Tyr701 induces Stat1 dimerization, nuclear translocation and DNA binding (4). Stat1 protein exists as a pair of isoforms, Stat1α (91 kDa) and the splice variant Stat1β (84 kDa). In most cells, both isoforms are activated by IFN-α, but only Stat1α is activated by IFN-γ. The inappropriate activation of Stat1 occurs in many tumors (5). In addition to tyrosine phosphorylation, Stat1 is also phosphorylated at Ser727 through a p38 mitogen-activated protein kinase (MAPK)-dependent pathway in response to IFN-α and other cellular stresses (6). Serine phosphorylation may be required for the maximal induction of Stat1-mediated gene activation.

  1. Heim, M.H. (1999) J. Recept. Signal. Transduct. Res. 19, 75-120.
  2. Durbin, J.E. et al. (1996) Cell 84, 443-450.
  3. Meraz, M.A. et al. (1996) Cell 84, 431-442.
  4. Ihle, J.N. et al. (1994) Trends Biochem. Sci. 19, 222-227.
  5. Frank, D.A. (1999) Mol. Med. 5, 432-456.
  6. Wen, Z. et al. (1995) Cell 82, 241-250.

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