Toll-like receptor

Toll-like receptor

Toll-like receptors (TLRs) are a class of proteins that play a key role in the immune system. They are single, membrane-spanning, non-catalytic receptors usually expressed in sentinel cells such as macrophages and dendritic cells, that recognize structurally conserved molecules derived from microbes.

Function

TLRs are a type of pattern recognition receptor (PRR) and recognize molecules that are broadly shared by pathogens but distinguishable from host molecules, collectively referred to as pathogen-associated molecular patterns (PAMPs). TLRs together with the Interleukin 1 receptors (IL-1Rs) form a receptor superfamily, known as the "interleukin-1 receptor / Toll-like receptor superfamily", all of which have in common a so-called TIR domain.

Structure

TLRs are present in vertebrates, as well as in invertebrates. Mammalian TLRs are divided into six families based on their genetic and functional similarities: TLR1, TLR3, TLR4, TLR5, TLR7 and TLR11. Each TLR is characterized by its extracellular leucine-rich repeat (LRR) domain and a cytoplasmic Toll/interleukin-1 receptor (TIR) domain.

Role in disease

TLRs are involved in diseases such as cancer, inflammatory bowel disease, asthma, and autoimmune diseases. They are also implicated in the immune response to viral infections.

See also

• Innate immune system
• Adaptive immune system
• Pattern recognition receptor
• Pathogen-associated molecular patterns

References

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  TLR3 structure
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  TLR2
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  Toll Pathway of Drosophila melanogaster
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  Toll-Like Receptors (TLRs)
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  Toll-like receptor pathways
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  History of TLRs