• Purity

  >95%, 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 enhance IL-18 BP inhibition of IL-18-induced IFN-gamma release by KG?1 human acute myelogenous leukemia cells. Bufler, P.     et al. (2002) PNAS     99:13723. The ED    ₅₀ for this effect is 2.5-12.5 μg/mL.

• Source

  E. coli-derived Val46-Asp218

• Accession #

• N-terminal Sequence    
  Analysis

  Val46

• Predicted Molecular Mass

  19.4 kDa

• SDS-PAGE

  25 kDa, reducing conditions

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.

Background: IL-37b/IL-1F7b

Human Interleukin 1 family member 7 (IL-1F7), also named FIL-1 zeta, IL-37, IL-1H4, IL-1HL and IL-1RP1, is an anti-inflammatory member of the IL-1 cytokine family. IL-1F7 shares approximately 21%, 24%, and 30% aa sequence identity with mature IL-1 alpha, IL-1 beta and IL-1ra, respectively. Mouse IL-1F7 has not been reported, but human IL-1F7 is active on mouse cells. Five isoforms (IL-1F7a through e) are generated through alternative exon usage and have distinct expression profiles (1?5). Like IL-1 alpha, IL-1 beta and IL-18, all of the IL-1F7 variants lack a typical signal peptide. The longest IL-1F7 transcript is the basis for the product offered here. This product, also referred to as IL-1F7b, or IL-1F7 isoform 1, is normally generated from a 218 amino acid (aa) proprotein that consists of a 45 aa propeptide plus a 173 aa mature region that is cleaved by caspase-1 to generate the 32 kDa mature form (aa 46-218) (6). IL-1F7 is up-regulated by inflammatory stimuli in peripheral blood mononuclear cells (7). Experimental overexpression of IL-1F7b   in vivo limits the inflammatory response and protects mice from colitis and LPS-induced shock (7, 8). Both unprocessed and mature IL-1F7b can form homodimers in solution (6, 7). Although IL-1F7b will bind to IL-18 R alpha with low affinity, this has no effect on IL?18 receptor activity (4, 6, 9). Alternatively, IL-1F7b will also bind to IL-18 BP, generating a complex that interacts with IL-18R beta. This has the effect of attenuating IL?18 activity via the IL-18 receptor (9). IL-1F7b can also function intracellularly. Following LPS-induced cleavage of its propeptide, IL-1F7b associates with Smad3 and translocates to the nucleus. This results in a reduction of pro-inflammatory cytokine secretion (10).

• References:

1. Smith, D.E. et al. (2000) J. Biol Chem 275:1169.

2. Kumar S. et al. (2000) J. Biol Chem 275:10308.

3. Busfield S.J. et al. (2000) Genomics 66:213.

4. Pan, G. et al. (2000) Cytokine 13:1.

5. Boraschi, D. et al. (2011) Eur. Cytokine Netw. 22:127.

6. Kumar S. et al. (2002) Cytokine 18:61.

7. Nold, M.F. et al. (2010) Nat. Immunol. 11:1014.

8. McNamee, E.N. et al. (2011) Proc. Natl. Acad. Sci. USA 108:16711.

9. Bufler, P. et al. (2002) Proc. Natl. Acad. Sci. USA 99:13723.

10. Sharma, S. et al. (2008) J. Immunol. 180:5477.

• Long Name:

  Interleukin 37 Isoform B

• Entrez Gene IDs:

  27178 (Human)

• Alternate Names:

  IL37b; IL-37b