Cell Signaling Technology

Product Pathways - Jak/Stat Pathway

Phospho-Jak2 (Tyr221) Antibody #3774

Applications Reactivity MW (kDa) Source
W H M (R) 125 Rabbit

Applications Key:  W=Western Blotting
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-Jak2 (Tyr221) Antibody detects endogenous levels of Jak2 only when phosphorylated at tyrosine 221.

Source / Purification

Polyclonal antibodies are produced by immunizing rabbits with a synthetic phospho-peptide (KLH-coupled) corresponding to residues surrounding Tyr221 of human Jak2. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of extracts from HT29 and CTLL2 cells, untreated or treated with IL-4 or GM-CSF (10 minutes), using Phospho-Jak2 (Tyr221) Antibody. Both cell lines contain a high level of constitutively active Jak2.

Background

Members of the Janus family of tyrosine kinases (Jak1, Jak2, Jak3 and Tyk2) are activated by ligands binding to a number of associated cytokine receptors (1). Upon cytokine receptor activation, Jak proteins become autophosphorylated and phosphorylate their associated receptors to provide multiple binding sites for signaling proteins. These associated signaling proteins, such as Stats (2), Shc (3), insulin receptor substrates (4) and focal adhesion kinase (FAK) (5), typically contain SH2 or other phospho-tyrosine-binding domains.

Jak2 is autophosphorylated at Tyr1007/1008 in the putative activation loop during cytokine signaling (6). Tyr221 and 570 have also been shown to be prominant sites for autophosphorylation (7,8). Mutational analysis suggests that phosphorylation at Tyr221 may increase kinase activity, while phosphorylation at Tyr570, which lies within the JH2 inhibitory domain, may contribute to inhibiting Jak2 activity. In addition, Tyr813 was identified as a site for autophosphorylation critical for the activation of Jak2 by the SH2 domain-containing protein SH2-Bbeta (9).

  1. Leonard, W.J. and O'Shea, J.J. (1998) Annu. Rev. Immunol. 16, 293-322.
  2. Darnell, J.E. (1997) Science 277, 1630-1635.
  3. VanderKuur, J. et al. (1995) J. Biol. Chem. 270, 7587-7593.
  4. Argetsinger, L.S. et al. (1995) J. Biol. Chem. 270, 14685-14692.
  5. Zhu, T. et al. (1998) J. Biol. Chem. 273, 10682-10689.
  6. Gauzzi, M. C. et al. (1996) J. Biol. Chem. 271, 20494-20500.
  7. Argetsinger, L. S. et al. (2004) Mol. Cell. Biol. 24, 4955-4967.
  8. Feener, E. P. et al. (2004) Mol. Cell. Biol. 24, 4968-4978.
  9. Kurzer, J. H. et al. (2004) Mol. Cell. Biol. 24, 4557-4570.

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