Cell Signaling Technology

Product Pathways - Glucose Metabolism

Phospho-IRS-1 (Ser332/336) Antibody #2580

Applications Reactivity Sensitivity MW (kDa) Source
W R (H) (M) Transfected Only 180 Rabbit

Applications Key:  W=Western Blotting
Reactivity Key:  H=Human  M=Mouse  R=Rat
Species cross-reactivity is determined by Western blot.

Specificity / Sensitivity

Phospho-IRS-1 (Ser332/336) Antibody detects transfected levels of IRS-1 only when phosphorylated at Ser332/336. This antibody does not cross-react with other related phosphoproteins.

Source / Purification

Polyclonal antibodies are produced by immunizing rabbits with a synthetic phosphopeptide (KLH-coupled) corresponding to residues surrounding Ser332/336 of mouse IRS-1 (equivalent to Ser337/341 of human IRS-1). Antibodies are purified by peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of cell extracts from CHO cells overexpressing insulin receptor and IRS-1, untreated or treated with insulin, using Phospho-IRS-1 (Ser332/336) Antibody (upper and middle) or IRS-1 Antibody #2382 (lower). The middle blot was treated with calf intestinal phosphatase (CIP) before antibody probing.

Background

Insulin receptor substrate 1 (IRS-1) is one of the major substrates of the insulin receptor kinase (1). IRS-1 contains multiple tyrosine phosphorylation motifs that serve as docking sites for SH2 domain containing proteins that mediate the metabolic and growth promoting functions of insulin (2-4). IRS-1 also contains over 30 potential serine/threonine phosphorylation sites. Ser307 of IRS-1 is phosphorylated by JNK (5) and IKK (6) while Ser789 is phosphorylated by SIK-2, a member of the AMPK family (7). The PKC and mTOR pathways mediate phosphorylation of IRS-1 at Ser612 and Ser636/639, respectively (8,9). Phosphorylation of IRS-1 at Ser1101 is mediated by PKCθ and results in an inhibition of insulin signaling in the cell, suggesting a potential mechanism for insulin resistance in some models of obesity (10).

GSK-3-mediated IRS-1 serine phosphorylation leads to inhibition of insulin-stimulated IRS-1 signaling. Ser332 and Ser336 of IRS-1 are situated in a glycogen synthase kinase-3 (GSK-3) consensus motif (SXXXS), and it has been shown that Ser332 is the actual GSK-3 phosphorylation site while Ser336 provides a " priming" site necessary for GSK-3 action (11).

  1. Sun, X.J. et al. (1991) Nature 352, 73-77.
  2. Sun, X.J. et al. (1992) J. Biol. Chem. 267, 22662-22672.
  3. Myers Jr., M.G. et al. (1993) Endocrinology 132, 1421-1430.
  4. Wang, L.M. et al. (1993) Science 261, 1591-1594.
  5. Rui, L. et al. (1997) J. Clin. Invest. 107, 181-189.
  6. Gao, Z. et al. (2002) J. Biol. Chem. 277, 48115-48121.
  7. Horike, N. et al. (2003) J. Biol. Chem. 278, 18440-18447.
  8. Ozes, O.N. et al. (2001) Proc. Natl. Acad. Sci. USA 98, 4640-4645.
  9. De Fea, K. and Ruth, R.A. (1997) Biochemistry 36, 12939-12947.
  10. Li, Y. et al. (2004) J. Biol. Chem. 279, 45304-45307.
  11. Liberman, Z. and Eldar-Finkelman, H. (2005) J. Biol. Chem. 280, 4422-4428.

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This product is for in vitro research use only and is not intended for use in humans or animals. This product is not intended for use as therapeutic or in diagnostic procedures.

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