Pattern Recognition receptors

Unless otherwise stated all data on this page refer to the human proteins. Gene information is provided for human (Hs), mouse (Mm) and rat (Rn).


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Pattern recognition receptors (PRR, [14]) participate in the innate immune response to microbial agents, the stimulation of which leads to activation of intracellular enzymes and regulation of gene transcription. PRR include both cell-surface and intracellular proteins, including toll-like receptors (TLR), nucleotide-binding oligomerization domain-like receptors (NLR, also known as NOD-like receptors) and the mannose receptor family (ENSFM00250000004089). PRR may be divided into signalling-associated members, identified here, and endocytic members (such as the mannose receptor family), the function of which appears to be to recognise particular microbial motifs for subsequent cell attachment, internalisation and destruction.

PRRs express multiple leucine-rich regions to bind a range of microbially-derived ligands, termed PAMPs or pathogen-associated molecular patterns, which includes peptides, carbohydrates, peptidoglycans, lipoproteins, lipopolysaccharides, and nucleic acids.

Toll-like receptor family


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Members of this family share significant homology with the interleukin-1 receptor family and appear to require dimerization either as homo- or heterodimers for functional activity. Heterodimerization appears to influence the potency of ligand binding substantially (e.g. TLR1/2 and TLR2/6, [15-16]). TLR1, TLR2, TLR4, TLR5, TLR6 and TLR11 are cell-surface proteins, while other members are associated with intracellular organelles, signalling through the MyD88-dependent pathways (with the exception of TLR3). As well as responding to exogenous infectious agents, it has been suggested that selected members of the family may be activated by endogenous ligands, such as hsp60 (HSPD1, P10809) [10].


TLR1 Show summary »

TLR2 Show summary »

TLR3 Show summary »

TLR4 Show summary »

TLR5 Show summary »

TLR6 Show summary »

TLR7 Show summary » More detailed page

TLR8 Show summary »

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NOD-like receptor family


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Structural analysis has identified a common motif of a mid-peptide located nucleotide-binding and oligomerization (NACHT) domain, which allows division of NOD-like receptors into three subfamilies, NLRC (or NODs), NLRP (or NALP) and IPAF [12]. NLRC members are named on the basis of a sequence motif expressed at their N-termini, the caspase recruitment domain (CARD), while NLRP members have a pyrin domain. NLRs express C-terminal leucine-rich regions which have regulatory function and appear to recognize the microbial products to which the NLRs respond. NLRC family members recruit a serine/threonine kinase RIPK2 (receptor-interacting serine/threonine kinase 2, O43353, also known as CARD3, CARDIAK, RICK, RIP2) leading to signalling through NFκB and MAP kinase. NLRP family members, upon activation, recruit adaptor proteins (e.g. ASC, also known as PYCARD, CARD5, TMS-1, Q9ULZ3). Activated NLRs associate in multiprotein complexes, known as inflammasomes [12], allowing the recruitment of caspases.


NLRC1 Show summary »

NLRC2 Show summary »

NLRC3 Show summary »

NLRC5 Show summary »

NLRX1 Show summary »

CIITA Show summary »

NLRP1 Show summary »

NLRP2 Show summary »

NLRP3 Show summary »

NLRP4 Show summary »

NLRP5 Show summary »

NLRP6 Show summary »

NLRP7 Show summary »

NLRP8 Show summary »

NLRP9 Show summary »

NLRP10 Show summary »

NLRP11 Show summary »

NLRP12 Show summary »

NLRP13 Show summary »

NLRP14 Show summary »

IPAF Show summary »

NAIP Show summary »


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