• Purity

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

• Endotoxin Level

  <0.1 EU per 1 μg of the protein by the LAL method.  

• Activity

  Measured by its ability to inhibit poly I:C induced IL-8 secretion by HEK293 human embryonic kidney cells transfected with TLR3. The ED    ₅₀ for this effect is 5-10 μg/mL in the presence of 10 μg/mL of poly I:C.

• Source

  Mouse myeloma cell line, NS0-derived Lys27-Ser711, with a C-terminal 10-His tag

• Accession #

• N-terminal Sequence    
  Analysis

  Lys27

• Predicted Molecular Mass

  79.2 kDa

• SDS-PAGE

  110-120 kDa, reducing conditions

Background: TLR3

Human TLR3 is a 116 kDa type I transmembrane glycoprotein that belongs to the mammalian Toll-Like Receptor family of pathogen pattern recognition molecules (1, 2). There are at least eleven mouse and ten human members that activate the innate immune system following exposure to a variety of microbial species (3). The human TLR3 cDNA encodes a 904 amino acid (aa) precursor that contains a 23 aa signal sequence, a 681 aa extracellular domain (ECD), a 21 aa transmembrane segment, and a 179 aa cytoplasmic region (4). The horseshoe shaped ECD (5, 6) contains 23 leucine rich repeats, and the cytoplasmic domain contains one Toll/IL-1 receptor (TIR) domain. The ECD of human TLR3 shares 80%, 79%, and 77% aa sequence identity with the ECD of rat, mouse, and bovine TLR3, respectively. TLR3 is found in phagosomes (7), where the acidic pH enables binding of internalized double stranded RNA and mRNA from viruses, parasites, and necrotic virally-infected cells (8 - 11). Ligand binding by TLR3 induces receptor dimerization (5, 6, 8) leading to the release of inflammatory cytokines and dendritic cell maturation (9, 11 - 13). TLR3 is expressed in dendritic cells, macrophages, microglia, and astrocytes (13 - 15) and is upregulated by IFN-beta and LPS (9, 14). TLR3 expression is also induced by lung fibroblasts and epithelial cells by respiratory syncytial virus infection (12).

• References:

1. Sen, G.C. and S.N. Sarkar (2005) Cytokine Growth Factor Rev. 16:1.

2. Schroder, M. and A.G. Bowie (2005) Trends Immunol. 26:462.

3. Hopkins, P.A. and S. Sriskandan (2005) Clin. Exp. Immunol. 140:395.

4. Rock, F.L. et al. (1998) Proc. Natl. Acad. Sci. 95:588.

5. Choe, J. et al. (2005) Science 309:581.

6. Bell, J.K. et al. (2005) Proc. Natl. Acad. Sci. 102:10976.

7. Nishiya, T. et al. (2002) J. Biol. Chem. 280:37107.

8. de Bouteiller, O. et al. (2005) J. Biol. Chem. 280:38133.

9. Alexopoulou, L. et al. (2001) Nature 413:732.

10. Aksoy, E. et al. (2005) J. Biol. Chem. 280:277.

11. Kariko, K. et al. (2004) J. Biol. Chem. 279:12542.

12. Rudd, B.D. et al. (2005) J. Virol. 79:3350.

13. Farina, C. et al. (2005) J. Neuroimmunol. 159:12.

14. Heinz, S. et al. (2003) J. Biol. Chem. 278:21502.

15. Wang, T. et al. (2004) Nat. Med. 10:1366.

• Long Name:

  Toll-like Receptor 3

• Entrez Gene IDs:

  7098 (Human); 142980 (Mouse); 364594 (Rat)

• Alternate Names:

  CD283 antigen; CD283; TLR3; toll-like receptor 3