TLR 3

Toll-like receptor 3
File:TLR3 structure.png The structure of TLR3 covered with sugars
Available structures PDB Ortholog search: Template:Homologene2PDBe PDBe, Template:Homologene2uniprot RCSB List of PDB id codes 1ziw​, 2a0z​
Identifiers
Symbols	TLR3 ; CD283
External IDs	Template:OMIM5 Template:MGI HomoloGene: 20696
Gene ontology Molecular function Template:GNF GO Template:GNF GO Template:GNF GO Cellular component Template:GNF GO Template:GNF GO Biological process Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO Template:GNF GO
RNA expression pattern
File:PBB GE TLR3 206271 at tn.png
More reference expression data
Orthologs
Template:GNF Ortholog box
Species	Human	Mouse
Entrez	n/a	n/a
Ensembl	n/a	n/a
UniProt	n/a	n/a
RefSeq (mRNA)	n/a	n/a
RefSeq (protein)	n/a	n/a
Location (UCSC)	n/a	n/a
PubMed search	n/a	n/a

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.

Structure

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.

Despite being a glycoprotein, TLR3 crystallises readily - a prerequisite for structural analysis by x-ray crystallography.

Further reading

• Lien E, Ingalls RR (2002). "Toll-like receptors". Crit. Care Med. 30 (1 Suppl): S1–11. PMID 11782555.