Toll-like receptor 3
|The structure of TLR3 covered with sugars|
|RNA expression pattern|
TLR 3 is a member of the Toll-like receptor family of pattern recognition receptors of the innate immune system. Discovered in 2001, TLR3 recognizes double-stranded RNA, a form of genetic information carried by some viruses such as influenza. Upon recognition, TLR 3 induces the activation of NF-kB to increase production of type I interferons which signal other cells to increase their antiviral defenses. Double-stranded RNA is also recognised by the cytoplasmic receptors RIG-I and MDA-5.
The structure of TLR3 was reported in June 2005 by researchers at The Scripps Research Institute. TLR3 forms a large horseshoe shape that contacts with a neighboring horseshoe, forming a "dimer" of two horseshoes. Much of the TLR3 protein surface is covered with sugar molecules, making it a glycoprotein, but on one face (including the interface between the two horseshoes), there is a large sugar-free surface. This surface also contains two distinct patches rich in positively-charged amino acids, which may be a binding site for negatively-charged double-stranded RNA.
- ↑ Alexopoulou L, Holt A, Medzhitov R, Flavell R (2001). "Recognition of double-stranded RNA and activation of NF-kappaB by Toll-like receptor 3.". Nature 413 (6857): 732-8. PMID 11607032.
- ↑ Choe J, Kelker M, Wilson I (2005). "Crystal structure of human toll-like receptor 3 (TLR3) ectodomain.". Science 309 (5734): 581-5. PMID 15961631.
- Lien E, Ingalls RR (2002). "Toll-like receptors.". Crit. Care Med. 30 (1 Suppl): S1-11. PMID 11782555.
Transmembrane receptors: immune receptors
|Cytokine receptor||Type I: interleukin (IL-2, IL-3) - CSF (Erythropoietin, GM-CSF, G-CSF) - Glycoprotein 130/Oncostatin M - Leukemia inhibitory factor - common subunits (Common gamma chain, CSF2RB)|
Chemokine - TGF-beta - Tumor necrosis factor
|Pattern recognition/Toll-like||TLR 1 - TLR 2 - TLR 3 - TLR 4 - TLR 5 - TLR 6 - TLR 7 - TLR 8 - TLR 9 - TLR 10|
|Fc receptor||ε (FcεRI, FcεRII) - γ (FcγRI, FcγRII, FcγRIII) - α/μ (FcαRI, Fcα/μR) - Neonatal|
|Lymphocyte homing receptor||CD44 - L-selectin - VLA-4 - LFA-1|
|other||Antigen receptor (B-cell, T cell) - Complement - Formyl peptide - Immunophilins - Integrin - Killer-cell immunoglobulin-like - Scavenger|
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