TLR 3

Toll-like receptor 3
250px
The structure of TLR3 covered with sugars
Available structures: 1ziw, 2a0z
Identifiers
Symbol(s)	TLR3; CD283
External IDs	OMIM: 603029 MGI: 2156367 Homologene: 20696
Gene ontology Molecular Function: • double-stranded RNA binding • transmembrane receptor activity • protein binding Cellular Component: • integral to plasma membrane • membrane Biological Process: • inflammatory response • hyperosmotic response • signal transduction • activation of NF-kappaB-inducing kinase • detection of virus • defense response to bacterium • positive regulation of I-kappaB kinase/NF-kappaB cascade • positive regulation of interferon-gamma biosynthetic process • innate immune response • positive regulation of interferon-alpha biosynthetic process • positive regulation of interferon-beta biosynthetic process • negative regulation of osteoclast differentiation • positive regulation of JNK cascade
RNA expression pattern
250px More reference expression data
Orthologs
	Human	Mouse
Entrez	7098	142980
Ensembl	ENSG00000164342	ENSMUSG00000031639
Uniprot	O15455	Q3TM31
Refseq	NM_003265 (mRNA) NP_003256 (protein)	NM_126166 (mRNA) NP_569054 (protein)
Location	Chr 4: 187.23 - 187.24 Mb	Chr 8: 46.89 - 46.91 Mb
Pubmed search	[1]	[2]

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.