• Purity

  >90%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.10 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its ability to inhibit the IL-18-induced response of mouse T cells. The ED    ₅₀ for this effect is 0.1‑0.4 µg/mL in the presence of 0.5 ng/mL of rmIL-18.

• Source

  Mouse myeloma cell line, NS0-derived

  Mouse IL-18 BPd/Fc (Thr27 - Ala191) & (Ala29 - Ala191) Accession # AAD17194	IEGRMD	Human IgG1 (Pro100 - Lys330)
  N-terminus		C-terminus

• Accession #

• N-terminal Sequence    
  Analysis

  Thr27 & Ala29

• Structure / Form

  Disulfide-linked homodimer

• Predicted Molecular Mass

  44.5 kDa (monomer)

• SDS-PAGE

  60-70 kDa, reducing conditions

Background: IL-18 BPd

Interleukin 18 binding protein (IL-18 BP) is a secreted glycoprotein, which functions as an IL-18 antagonist by binding to IL-18 and blocking its biological activity. IL-18 BP bears no amino acid sequence homology to the membrane-associated IL-18 and IL-1 receptor proteins. The gene for human IL-18 BP has been localized to chromosome 11q13. It encodes for at least four isoforms by alternative splicing. The IL-18 BP isoforms a and c each contain one immunoglobulin (Ig)-like C2-type domain while isoforms b and d lack a complete Ig domain. The complete Ig domain has been shown to be essential to the binding and neutralizing properties of the binding proteins. Two isoforms of mouse IL18 BP (c and d) containing the complete Ig domain have also been isolated and shown to neutralize IL-18 bioactivity. Human and mouse IL-18 BPs share approximately 61% amino acid sequence identity. Several poxviruses also encode proteins with sequence similarity to the human and mouse IL-18 BP. Viral IL-18 BPs have been shown to bind and inhibit IL-18 responses and may be involved in modulating host immune responses. The expression of IL-18 BP is markedly up-regulated by IFN-gamma, suggesting that IL-18 activity is modulated by a negative feedback mechanism mediated by IL-18 BP.

• References:

1. Muh, H. et al. (2000) Biochem. Biophys. Res. Commun. 267:960.

2. Kim, S-H. et al. (2000) Proc. Nat. Acad. Sci. USA 97:1190.

3. Calderara, S. et al. (2001) Virology 279:22.

• Long Name:

  Interleukin 18 Binding Protein Isoform d

• Entrez Gene IDs:

  10068 (Human); 16068 (Mouse)

• Alternate Names:

  IL18 BPd; IL-18 BPd