• Purity

  >95%, by SDS-PAGE under reducing conditions and visualized by silver stain

• Endotoxin Level

  <0.01 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured in a cell proliferation assay using TF‑1 human erythroleukemic cells. Kitamura, T.     et al. (1989) J. Cell Physiol.     140:323. The ED    ₅₀ for this effect is 0.5-2.5 ng/mL.

• Source

  E. coli-derived Gly21-Asn132

• Accession #

• N-terminal Sequence    
  Analysis

  Gly21

• Predicted Molecular Mass

  12.3 kDa

• SDS-PAGE

  9 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-13

Interleukin-13 (IL-13) is a monomeric 17 kDa immunoregulatory cytokine that plays a key role in the pathogenesis of allergy, cancer, and tissue fibrosis. It is secreted by several helper T cell subsets, NK cells, mast cells, eosinophils, basophils, and visceral smooth muscle cells (1‑3). Mature human IL-13 shares approximately 58% amino acid sequence identity with mouse and rat IL-13. Despite the low homology, it exhibits cross‑species activity between human, mouse, and rat (4). IL-13 suppresses the production of proinflammatory cytokines and other cytotoxic substances by macrophages, fibroblasts, and endothelial cells. On B cells, it promotes cellular activation, immunoglobulin class switching to IgE, and the up‑regulation of CD23/Fc epsilon RII (1, 5). IL-13 binds with low affinity to the transmembrane IL-13 R alpha 1 which then forms a signaling complex with the transmembrane IL-4 R alpha (6‑8). This high affinity receptor complex also functions as the type 2 IL-4 receptor (6, 7). IL‑13 R alpha 2 inhibits responses to both IL-13 and IL-4. It binds IL-13 with high affinity (9, 10) and prevents IL-13 from signaling through the IL-13 R alpha 1/IL-4 R alpha complex (11, 12). It also blocks signaling through IL-4-occupied IL-13 R alpha 1/IL-4 R alpha receptor complexes (12, 13). In addition, IL-13-bound IL-13 R alpha 2 can directly promote tumor cell invasiveness and the development of tissue fibrosis (14‑16).

• References:

1. Saggini, A. et al. (2011) Int. J. Immunopathol. Pharmacol. 24:305.

2. Gallo, E. et al. (2012) Eur. J. Immunol. 42:2322.

3. Liang, H.E. et al. (2012) Nat. Immunol. 13:58.

4. Ruetten, H. and C. Thiemermann (1997) Shock 8:409.

5. McKenzie, A.N. et al. (1993) Proc. Natl. Acad. Sci. USA 90:3735.

6. Aman, M.J. et al. (1996) J. Biol. Chem. 271:29265.

7. Zurawski, S.M. et al. (1995) J. Biol. Chem. 270:13869.

8. Andrews, A.L. et al. (2002) J. Biol. Chem. 277:46073.

9. Chen, W. et al. (2009) J. Immunol. 183:7870.

10. Daines, M.O. et al. (2007) J. Allergy Clin. Immunol. 119:375.

11. Kasaian, M.T. et al. (2011) J. Immunol. 187:561.

12. Andrews, A.-L. et al. (2006) J. Allergy Clin. Immunol. 118:858.

13. Rahaman, S.O. et al. (2002) Cancer Res. 62:1103.

14. Fujisawa, T. et al. (2009) Cancer Res. 69:8678.

15. Fujisawa, T. et al. (2011) Int. J. Cancer 131:344.

16. Fichtner-Feigl, S. et al. (2006) Nat. Med. 12:99.

• Long Name:

  Interleukin 13

• Entrez Gene IDs:

  3596 (Human); 16163 (Mouse); 116553 (Rat); 574325 (Primate)

• Alternate Names:

  ALRHMGC116789; BHR1interleukin-13; IL13; IL-13; IL-13MGC116788; interleukin 13; MGC116786; NC30; P600