• Purity

  >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.

• Endotoxin Level

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

• Activity

  Measured in an anti-viral assay using HepG2 human hepatocellular carcinoma cells infected with encephalomyocarditis (EMC) virus. Sheppard, P.     et al. (2003) Nat. Immunol.     4:63. The ED    ₅₀ for this effect is 1-5 ng/mL.

• Source

  Chinese Hamster Ovary cell line, CHO-derived Arg30-Val200, with the variant of Lys74Arg and a C-terminal 6-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  Arg30

• Predicted Molecular Mass

  20.1 kDa

• SDS-PAGE

  22 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-28B/IFN-lambda 3

IL-28B (also named interferon-lambda 3, IFN-lambda 3), IL-28A (IFN-lambda 2) and IL-29 (IFN-lambda 1) are type III interferons that are class II cytokine receptor ligands (1-4). They are distantly related to members of the IL-10 family and type I IFN family (1- 4). Human IL-28B cDNA encodes a 200 amino acid (aa) protein with a 25 aa signal peptide and a 175 aa mature protein that lacks N-glycosylation sites. Mature human IL-28B shares 64% and 75% aa sequence identity with mouse and canine IL-28B, respectively, and is active across species (5). Human IL-28B shares 94% and 69% aa identity with human IL-28A and IL‑29, respectively (4). Type III interferons are widely expressed, but are mainly produced by antigen presenting cells in response to viruses and double-stranded RNA that interact with Toll-like receptors or RIG-1 family helicases (2-6). They signal through a widely expressed receptor that is a heterodimer of the IL-10 receptor beta (IL-10 R beta ) and IL-28 receptor alpha (IL-28 R alpha ; also called IFN-lambda R1) (2, 3, 7, 9). Interaction of either type I or type III IFNs with their receptors activates similar pathways, including JAK tyrosine kinase activation, STAT phosphorylation and formation of the IFN-stimulated regulatory factor 3 (ISGF-3) transcription factor complex (1-3). Both type I and III IFNs induce anti‑viral activity and up‑regulate MHC class I antigen expression (2-6). Cell lines responsive to type III IFNs are also responsive to type I IFNs, but in general, higher concentrations of type III IFNs are needed for similar in vitro responses (8). In vivo, however, type III IFNs enhance levels of IFN-gamma in serum, suggesting that the robust anti-viral activity of type III IFNs may stem in part from activation of the immune system (5, 7). Anti-proliferative and antitumor activity in vivo has also been shown for type III IFNs (9-11).

• References:

1. Chen, Q. et al. (2006) Vitam. Horm. 74:207.

2. Sheppard, P. et al. (2003) Nat. Immunol. 4:63.

3. Kotenko, S.V. et al. (2003) Nat. Immunol. 4:69.

4. Bartlett, N.W. et al. (2005) J. Gen. Virol. 86:1589.

5. Ank, N. et al. (2006) J. Virol. 80:4501.

6. Onoguchi, K. et al. (2007) J. Biol. Chem. 282:7576.

7. Siebler, J. et al. (2007) Gastroenterology 132:358.

8. Meager, A. et al. (2005) Cytokine 31:109.

9. Lasfar, A. et al. (2006) Cancer Res. 66:4468.

10. Sato, A. et al. (2006) J. Immunol. 176:7686.

11. Zitzmann, K. et al. (2006) Biochem. Biophys. Res. Commun. 344:1334.

• Long Name:

  Interleukin 28B

• Entrez Gene IDs:

  282617 (Human); 338374 (Mouse)

• Alternate Names:

  interleukin-28B; IFN-lambda 3; IL28B; IL-28B; IL28C; interferon, lambda 3