TLR 3

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toll-like receptor 3
Identifiers
Symbol	TLR3
HUGO	11849
Entrez	7098
OMIM	603029
RefSeq	NM_003265
UniProt	O15455
Other data
Locus	Chr. 4 q35

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. Double-stranded RNA is also recognised by the cytoplasmic receptors RIG-I and MDA-5.

[edit] 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.

[edit] References

1. ^ 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. 
2. ^ Choe J, Kelker M, Wilson I (2005). "Crystal structure of human toll-like receptor 3 (TLR3) ectodomain.". Science 309 (5734): 581-5. PMID 15961631.