Encyclopedia of Cancer

Living Edition
| Editors: Manfred Schwab

TLR4

Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27841-9_5836-9

Definition

Toll-like receptor 4 is a protein that in humans is encoded by the TLR4 gene. TLR 4 is the first discovered human toll-like receptor. It recognizes endotoxin (i.e., lipopolysaccharide), an outer membrane component of gram-negative bacteria, that is composed of a conserved amphipathic lipid A component and of variable polysaccharides. The mechanism of TLR4 activation is quite complex and (unlike other TLRs) involves several auxiliary proteins (LBP, CD14) as well as a coreceptor (MD-2). It is in fact MD-2 and not TLR4 that directly recognizes and binds endotoxin. MD-2 is a soluble protein with a large hydrophobic pocket that represents the binding site for the acyl chains of lipid A. Lipid A is usually composed of six acyl chains, but only five of them bind into the hydrophobic pocket of MD-2. The sixth acyl chain protrudes out of the pocket and interacts with hydrophobic residues on TLR4. These interactions are crucial for MD-2/TLR4 heterodimerization and therefore...

Keywords

TLR4 Expression TLR4 Ligand TLR4 Activation Gastric Cancer Risk Endogenous TLR4 Ligand 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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References

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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Stanford University School of MedicineStanfordUSA