ISG15 ELISA Kit (Ubiquitin-Like Protein ISG15)

Full Name: ISG15 ELISA Kit (Ubiquitin-Like Protein ISG15)
Reactivity: Human
Sample Type: Biological Fluids, Plasma, Tissue Homogenates, Serum
Sensitivity: 18.75 pg/ml

INTRODUCTION

The 15-kDa protein is known as interferon-stimulated gene 15 (ISG15) it has two N- and C-terminal ubiquitin-like domains that are joined by a linker region. A beta-grasp fold and a conserved LRLRGG motif make up the C-terminal tail of each ubiquitin-like domain. ISG15 conjugation to target proteins depends on the C-terminal tail of the protein. It is a member of the interferon stimulated gene family.

The protein encoded is a ubiquitously expressed interferon stimulated gene (ISG) that is not part of the classical pathway. ISG15 shares similarity with heat shock protein 90 and tumor necrosis factor receptor 2. In addition, it binds to and inhibit histone deacetylase 2-3 complex activity that regulates transcriptional activation via histone acetylation.

The major purpose of ISG15 protein conjugates is to alter proteins by conjugation. It is covalently attached to lysine residues on target proteins during this process, which goes by the name of “isgylation” and is analogous to the ubiquitination process. . The ISG15 protein conjugates are then activated by the enzyme Igs, which is typically found in macrophages. Igs bind to the protein conjugates and leads to the release of a chemical that can kill or inhibit target proteins. Some ISG15s have been reported to cause direct cytotoxicity against tumor cells in some cases. It also plays a role as an antiviral agent through its potential use as a molecular drug carrier, which allows drugs to pass through cell membranes and enter cells without being degraded by enzymes in it.

INTENDED USE

Human ISG15 ELISA kit can be used to detect levels of ubiquitin-like protein ISG15 (interferon stimulating gene 15, G1P2, UCRP, alpha-inducible protein, ISG15 ubiquitin-like modifier) using human tissue homogenates, plasma, serum and other biological samples.

CONTENT

All reagents supplied need to be stored at 2 °C – 8 °C, unopened reagents will retain reactivity until expiration date. Do not use reagents beyond this date.

• One 96-Well Plate: Pre-coated with anti-ISG15 antibody.
• Standards: Lyophilized recombinant.
• Sample/Standard Dilution Buffer.
• Biotinylated-labelled Antibody.
• Antibody Dilution Buffer.
• HRP-Streptavidin Conjugate (SABC).
• SABC Dilution Buffer.
• TMB Substrate.
• Wash Buffer (25x).
• Plate Sealer.
• Product Instructions.

TYPICAL RESULTS

For the following ISG15 ELISA kit it is recommended that a standard curve is generated for each assay carried out.

Standard Curve: 0, 31.25, 62.5, 125, 250, 500, 1000, 2000 pg/ml.
Reactivity: Human
Sensitivity: 18.75 pg/ml
Range: 31.25 – 2000 pg/ml
Principle: Sandwich
Application: Research Use Only.

ASSAY CHARACTERISTICS

– Specificity: Highly specific for ISG15, no cross reactivity or interference between ISG15 and analogues was detected.
– Recovery: Serum (91 – 102%), EDTA Plasma (90 – 105%), Heparin Plasma (85 – 102%).
– Linearity: Serum (86 – 103%), EDTA Plasma (92 – 100%), Heparin Plasma (82 – 96%).
– Precison Intra-Assay: CV < 8%.
– Precison Inter-Assay: CV < 10%.
– Stability: Less than 10%.

REFERENCES

1. ISG15 in antiviral immunity and beyond. Nat Rev Microbiol. (2018) 16 (7): 423-439. Perng Y.C. and Lenschow D.J.
2. Ubiquitin-like Protein Conjugation: Structures, Chemistry, and Mechanism. Chem Rev. (2018) 118 (3): 889-918. Cappadocia L. and Lima C.D.
3. Ubiquitin like protein-ISG15 (interferon-stimulated gene of 15 kDa) in host defense against heart failure in a mouse model of virus-induced cardiomyopathy. Circulation. (2014) 130 (18): 1589-600. Rahnefeld A., et al.
4. Human intracellular ISG15 prevents interferon-α/β over-amplification and auto-inflammation. Nature. (2015) 517 (7532): 89-93. Zhang X., et al.

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