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TLR 2




Toll-like receptor 2
PDB rendering based on 1fyw.
Available structures: 1fyw, 1fyx, 1o77
Identifiers
Symbol(s) TLR2; CD282; TIL4
External IDs OMIM: 603028 MGI: 1346060 Homologene: 20695
RNA expression pattern

More reference expression data

Orthologs
Human Mouse
Entrez 7097 24088
Ensembl ENSG00000137462 ENSMUSG00000027995
Uniprot O60603 Q811T5
Refseq NM_003264 (mRNA)
NP_003255 (protein)
NM_011905 (mRNA)
NP_036035 (protein)
Location Chr 4: 154.84 - 154.85 Mb Chr 3: 83.92 - 83.93 Mb
Pubmed search [1] [2]

TLR-2 is the name for a biomolecule, which plays a role in the human immune system. It is a membrane protein, a receptor, which sits on the surface of certain cells and which can recognize native or foreign substances, and passes on appropriate signals to the cell and/or the nervous system.

The TLR-2 discussed here is member of a large family of homologous Toll-like receptors (TLRs).

Additional recommended knowledge

Contents

Impact

TLR-2 is a membrane receptor found at the surface of immune system cells that recognises many bacterial, fungal, viral and endogenous substances. Phagocytosis of bound materials takes place in endosome/phagosome and a cellular activation, so that the elements of the innate immune system take over such as macrophages, PMN and dendritic cells tasks of the nonspecific immune defense, B1a and form MZB first anti-bodies and uses in the process the specific anti-body formation. Here cytokine is involved e.g. Tumor necrosis factor-alpha (TNF α) and different interleukins (IL-1alpha, IL-1beta, IL-6, IL-8, IL-12). Before TLRs were discovered, some of the materials specified below were grouped under the term so-called "Moduline". By that rather Th1 appropriate cytokine pattern is seen in most experimental models an immune deviation this way, away of the Th2-expression. Conjugates are developed as vaccines or already used without a priori knowledge.

One only 2006 recognized characteristic is the expression of the TLR-2 on the Tregs (special form of the T-cells), which is brought equally to TCR determined proliferation and functional inactivity. Thereby, a disinhibition of the early inflammation phase and the specific anti-body formation is reached. After reduction of the exciter number many exciter-specific Tregs are present, which, now without TLR-2-Signal, become active and the specific like the inflammatory immune reaction to restrain (see also TGF beta, Interleukin 10). Older literature, which attributes a direct immune stimulation effect over TLR-2 to a given substance, must be interpreted under circumstances that the used TLR-2-knockouts has regularly quite few Tregs.

Functionally relevant polymorphism is described, which reduced to a function restriction and thus usually survival rate with infections/sepsis with Gram-positive bacteria leads in particular.

The signal transduction is represented in the article toll-like receptor.

Expression

TLR-2 is expressed on microglia, Schwann cells, monocytes, macrophages, dendritic cells, polymorphonuclear leukocytes, B-cells (B1a, MZB, B2), T-cells including regulatory T cells (CD4, CD25). TLR-2 is likewise in the epithelium of the bronchial tube and the alveoli.

Agonists

Agonist Organism
Lipoteichoic acid Gram-positive bacteria
Peptidoglycan Gram-negative and Gram-positive bacteria
atypical LPS Leptospirosis and Porphyromonas gingivalis
MALP-2 and MALP-404 (lipoproteins) Mycoplasma
- Chlamydophila pneumoniae
OspA Borrelia burgdorferi (Lyme disease)
Porin Haemophilus influenzae
Antigen mixtures Propionibacterium acnes
LcrV Yersinia
Lipomannan Mycobacterium: Mycobacterium tuberculosis
GPI anchor Trypanosoma cruzi
Lysophosphatidylserine Schistosoma mansoni
Lipophosphoglycan (LPG) Leishmania major
Zymosan Saccharomyces cerevisiae
- Malassezia (commensal yeast)
Antigen mixtures Aspergillus fumigatus, Candida albicans
hsp60, as peptide transporter and adjuvant for antigen presentation -
- Herpes simplex virus
- Varicella zoster virus
- Cytomegalovirus (CMV)
Hemagglutinin Measles

Further reading

  • Aderem A, Ulevitch RJ (2000). "Toll-like receptors in the induction of the innate immune response.". Nature 406 (6797): 782-7. doi:10.1038/35021228. PMID 10963608.
  • Muzio M, Polentarutti N, Bosisio D, et al. (2001). "Toll-like receptor family and signalling pathway.". Biochem. Soc. Trans. 28 (5): 563-6. PMID 11044375.
  • Hallman M, Rämet M, Ezekowitz RA (2002). "Toll-like receptors as sensors of pathogens.". Pediatr. Res. 50 (3): 315-21. PMID 11518816.
  • Dziarski R, Gupta D (2001). "Role of MD-2 in TLR2- and TLR4-mediated recognition of Gram-negative and Gram-positive bacteria and activation of chemokine genes.". J. Endotoxin Res. 6 (5): 401-5. PMID 11521063.
  • Lien E, Ingalls RR (2002). "Toll-like receptors.". Crit. Care Med. 30 (1 Suppl): S1-11. PMID 11782555.
  • Xu D, Komai-Koma M, Liew FY (2005). "Expression and function of Toll-like receptor on T cells.". Cell. Immunol. 233 (2): 85-9. doi:10.1016/j.cellimm.2005.04.019. PMID 15950961.
  • Lorenz E (2007). "TLR2 and TLR4 expression during bacterial infections.". Curr. Pharm. Des. 12 (32): 4185-93. PMID 17100621.
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "TLR_2". A list of authors is available in Wikipedia.
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