Cell Signaling Technology

Product Pathways - Protein Stability

ISG15 (22D2) Rabbit mAb #2758

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

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

Protocols

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

Monoclonal antibody is produced by immunizing animals with a synthetic peptide corresponding to amino acids at the amino terminus of human ISG15 protein.

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.

For Research Use Only. Not For Use In Diagnostic Procedures.

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