Recombinant Human ISG15 Protein, CF


Discontinued Product

UL-601 has been discontinued.
View all ISG15/UCRP products.
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Citations (3)

Recombinant Human ISG15 Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE under reducing conditions and visualized by Colloidal Coomassie® Blue stain
Recombinant Human ISG15 can be conjugated to substrate proteins via the subsequent actions of an ISG15-activating (E1) enzyme, an ISG15-conjugating (E2) enzyme, and an ISG15 ligase (E3). Reaction conditions will need to be optimized for each specific application. We recommend an initial Recombinant Human ISG15 concentration of 1-10 μM for conjugation reactions.
E. coli-derived human ISG15/UCRP protein
Accession #
Predicted Molecular Mass
17 kDa

Product Datasheets

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Carrier Free

What does CF mean?

CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.

What formulation is right for me?

In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.


Formulation Supplied as a solution in HEPES, NaCl, DTT and Glycerol.
Shipping The product is shipped with dry ice or equivalent. Upon receipt, store it immediately at the temperature recommended below.
Stability & Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
  • 12 months from date of receipt, -70 °C as supplied.
  • 3 months, -70 °C under sterile conditions after opening.
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Background: ISG15/UCRP

Interferon-stimulated Gene 15 (ISG15), also known as Ubiquitin Cross-reacting Protein (UCRP), is a Ubiquitin-like protein that is covalently coupled to target proteins in a process termed ISGylation. The mature form of ISG15 is a 156 amino acid (aa) polypeptide with a predicted molecular weight of 17 kDa. ISG15/UCRP exhibits 66% aa sequence identity with its mouse ortholog. Structurally, ISG15/UCRP consists of two tandem Ubiquitin-like domains that share a similar 3-dimensional structure with Ubiquitin and other Ubiquitin-like modifiers including NEDD8 and SUMO1. Modification of targets by ISG15/UCRP occurs in a stepwise enzymatic process similar to that of Ubiquitin. Enzymes regulating ISGylation include the activating (E1) enzyme UBE1L, the conjugating (E2) enzyme UbcH8, and ligases (E3) such as EFP/TRIM25 and HERC5 (1-4). Removal of ISG15/UCRP is catalyzed by the deconjugating enzyme UBP43/USP18 (5). Functionally, ISG15/UCRP has putative roles in the immune response and tumorigenesis. This is reflected by intracellular ISG15/UCRP targets that include Cyclin D1, tumor suppressor p63, IRF3, and a range of viral proteins (6-8). It is induced by type 1 interferons and microbial infection, and knockout mice exhibit an increased sensitivity to infection by some viruses (6). ISG15/UCRP can also be secreted by cells of the immune system and may act in a cytokine-like manner (9). For instance, it is produced by human granulocytes in response to mycobacterium exposure, and natural killer cells and T cells respond to extracellular ISG15/UCRP with IFN-gamma production (10). Further supporting a role in immune function, ISG15/UCRP mutations are associated with MSMD, an inherited disorder characterized by increased susceptibility to mycobacterial infection (10).

  1. Yuan, W. & R.M. Krug (2001) EMBO J. 20:362.
  2. Zhao, C. et al. (2004) Proc. Natl. Acad. Sci. USA 101:7578.
  3. Zou, W. & D.E. Zhang (2006) J. Biol. Chem. 281:3989.
  4. Wong, J.J. et al. (2006) Proc. Natl. Acad. Sci. USA 103:10735.
  5. Malakhov, M.P. et al. (2002) J. Biol. Chem. 277:9976.
  6. Zhang, D. & D.-E. Zhang (2011) J. Interferon Cytokine Res. 31:119.
  7. Jeon, Y.J. et al. (2012) J. Clin. Invest. 122:2622.
  8. Harty, R.N. et al. (2009) J. Innate. Immun. 1:397.
  9. Owashi, M. et al. (2003) Biochem. Biophys. Res. Commun. 309:533.
  10. Bogunovic, D. et al. (2012) Science 337:1684.
Long Name
ISG15 Ubiquitin-like Modifier
Entrez Gene IDs
9636 (Human); 100038882 (Mouse); 298693 (Rat)
Alternate Names
G1P2; G1P2interferon-induced 17-kDa/15-kDa protein; IFI15; IFI15hUCRP; interferon, alpha-inducible protein (clone IFI-15K); Interferon-induced 15 kDa protein; Interferon-induced 17 kDa protein; interferon-stimulated protein, 15 kDa; IP17; ISG15 ubiquitin-like modifier; ISG15; Ubiquitin cross-reactive protein; ubiquitin-like protein ISG15; UCRP; UCRPIP17

Citations for Recombinant Human ISG15 Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

3 Citations: Showing 1 - 3
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  1. ISG15 induces ESRP1 to inhibit lung adenocarcinoma progression
    Authors: T Qu, W Zhang, L Qi, L Cao, C Liu, Q Huang, G Li, L Li, Y Wang, Q Guo, Y Guo, D Ren, Y Gao, J Wang, B Meng, B Zhang, W Cao
    Cell Death Dis, 2020;11(7):511.
    Species: Mouse
    Sample Types: In Vivo
    Applications: In Vivo
  2. Interferon-stimulated gene 15 (ISG15) restricts Zika virus replication in primary human corneal epithelial cells
    Authors: PK Singh, S Singh, D Farr, A Kumar
    Ocul Surf, 2019;0(0):.
    Applications: Bioassay
  3. Interferon-stimulated gene 15 (ISG15) and ISG15-linked proteins can associate with members of the selective autophagic process, histone deacetylase 6 (HDAC6) and SQSTM1/p62.
    Authors: Nakashima H, Nguyen T, Goins W, Chiocca E
    J Biol Chem, 2015;290(3):1485-95.
    Species: Human
    Sample Types: Whole Cells
    Applications: Bioassay


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