Health Dictionary
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TLR 3
Introduction
TLR 3 is a member of the Toll-like receptor family of pattern recognition receptors of the innate immune system. Discovered in 2001,[1] 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.
Structure
Structure
The structure of TLR3 was reported in June 2005 by researchers at The Scripps Research Institute.[2] 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.
Despite being a glycoprotein, TLR3 crystallises readily – a prerequisite for structural analysis by x-ray crystallography.
References
References
- ↑ 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.