Cell Signaling Technology

Product Pathways - Protein Folding/Stability

ISG15 (22D2) Rabbit mAb #2758

Applications Reactivity Sensitivity MW (kDa) Source Isotype
W IP H Endogenous 15 Rabbit IgG

Applications Key:  W=Western Blotting  IP=Immunoprecipitation
Reactivity Key:  H=Human
Species enclosed in parentheses are predicted to react based on 100% sequence homology. Species cross-reactivity is determined by Western blot.

Specificity / Sensitivity

ISG15 (22D2) Rabbit mAb detects endogenous levels of the uncleaved precursor form of ISG15 protein. This antibody does not recognize the activated (cleaved) or conjugated forms of ISG15. The antibody does not cross-react with other ubiquitin family members, including ubiquitin, SUMO-1, SUMO-2, SUMO-3 and NEDD8.

Source / Purification

Polyclonal antibodies are produced by immunizing rabbits with a synthetic peptide (KLH-coupled) corresponding to amino acids from human ISG15 protein. Antibodies are purified by protein A and peptide affinity chromatography.

Western Blotting

Western Blotting

Western blot analysis of lysates from HeLa and A549 cells, untreated (-) or treated with IFN-α (1000 U/mL) (+) for 24 hours, using ISG15 (22D2) Rabbit mAb.

Background

Interferon-stimulated 15 kDa protein (ISG15), also known as ubiquitin cross-reactive protein (UCRP), is a member of the ubiquitin-like protein family and functions in various biological pathways from pregnancy to innate immune responses (1). Expression of ISG15 is stimulated by cellular exposure to type 1 interferons α and β, in addition to infection with viruses such as influenza B (2,3). After exposure to type I interferons, both lymphocytes and monocytes, in addition to some fibroblasts and epithelial cells, release ISG15 into culture medium (1,4). ISG15 has been shown to function as a cytokine, stimulating interferon γ secretion by monocytes and macrophages, proliferation of natural killer cells, and chemotactic responses in neutrophils (4,5). ISG15 has also been shown to function intracellularly, being covalently conjugated to other proteins by E1 (Ube1L), E2 (UbcH8) and E3 ligases via a multi-step process analogous to ubiquitination (6,7). ISG15 is removed from proteins by the ubiquitin processing protease Ubp43 (8). ISG15-protein conjugation (ISGylation) is induced by type 1 interferons, and target proteins include the serine protease inhibitor Serpin 2A, PLCγ1, ERK1/2, Jak1 and Stat1 (9,10). Unlike ubiquitination, ISGylation does not target proteins for degradation, rather ISGylation increases Jak1 and Stat1 activity, enhancing the cellular response to interferons (11).

  1. Ritchie, K.J. and Zhang, D.E. (2004) Semin. Cell Dev. Biol. 15, 237-246.
  2. Korant, B.D. et al. (1984) J. Biol. Chem. 259, 14835-14839.
  3. Haas, A.L. et al. (1987) J. Biol. Chem. 262, 11315-11323.
  4. Knight, E. and Cordova, B. (1991) J. Immunol. 146, 2280-2284.
  5. D'Cunha, J. et al. (1996) Proc. Natl. Acad. Sci. USA 93, 211-215.
  6. Loeb, K.R. and Haas, A.L. (1992) J. Biol. Chem. 267, 7806-7813.
  7. Zhao, C. et al. (2005) Proc. Natl. Acad. Sci. USA 102, 10200-10205.
  8. Malakhov, M.P. et al. (2002) J. Biol. Chem. 277, 9976-9981.
  9. Malakhov, M.P. et al. (2003) J. Biol. Chem. 278, 16608-16613.
  10. Hamerman, J.A. et al. (2002) J. Immunol. 168, 2415-2423.
  11. Malakhova, O.A. et al. (2003) Genes Dev. 17, 455-460.

Application References

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Companion Products

Rabbit Monoclonals Produced Using Epitomics® Technology, U.S. Patent No. 5,675,063.

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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