Antibodies and Recombinant Proteins
Pattern recognition receptors (PRRs) play a key role in the innate immune response by recognizing conserved pathogen associated molecular patterns (PAMPs) which are unique to each pathogen, and are essential molecular structures required for the pathogens survival. PRRs can identify a diverse collection of microbial pathogens, which include: bacteria, viruses, parasites, fungi, and protozoa. PRRs are primarily expressed by antigen presenting macrophage and dendritic cells but can also be expressed by other cells (both immune and non-immune cells). The PRRs are either localized on the cell surface to detect extracellular pathogens or within the endosomes and cellular matrix where they detect intracellular invading viruses. They are involved in activating pro-inflammatory signaling pathways, stimulating phagocytic responses (macrophages, neutrophils and dendritic cells) or binding to micro-organisms as secreted proteins.
In addition to the activation of immune cells upon recognition of PAMPs and DAMPs, PRRs trigger cell death mechanisms that result in the breakdown and ultimately death of a cell, leading to further release of DAMPs. To read more about which specific cell death mechanisms are induced and the markers involved that can be used to identify this process, go to our Pattern Recognition Receptors' Role In Cell Death page.
PRRs can be classified in a number of ways such as by function (e.g. signaling or endocytic) or by localization. Here we have classified the PRRs by localization and functional types:
Membrane bound PRRs
Toll-like receptors (TLR) – these are type 1 transmembrane receptors that have an extracellular domain which detects infecting pathogens. TLR1, 2, 4, and 6 recognize bacterial lipids, TLR3, 7 and 8 recognize viral RNA, TLR9 recognizes bacterial DNA, and TLR5 and 10 recognize bacterial or parasite proteins. Upon detection of a pathogen the intracellular domain of these receptors (TIR domain) initiates the activation of signalling pathways such as NF-kappa B pathway that stimulates the production of co-stimulatory molecules and cytokines involved in anti-microbial defence and inflammation.
C-type lectin receptors (CLR) - CLRs can be grouped as either group I mannose receptor family e.g. CD206 or group II asialoglycoprotein receptor family e.g. CD209 (DC-SIGN). Mannose is commonly found on viruses, mycobacteria and fungi, whereas fucose is common for bacteria and parasites (helminths), and glucans are present on mycobacteria and fungi (Dectin-1 is a C-type lectin glucan receptor).
Cytoplasmic (intracellular) PRRs
Nucleotide oligomerization (NOD) like receptors (NLR) - these include NODs (NOD1 and NOD2) which recognize bacterial peptidoglycan motifs and NALPs which also recognize microbial pathogens. These NLRs are involved in the regulation of inflammation and apoptosis.
Retinoic acid-inducible gene I (RIG-I) like receptors (RLR) - RIG-I, melanoma differentiation-associated gene 5 (MDA5) and DDX3 help recognize viral RNA. These receptors are RNA Helicases which activate antiviral signalling and LGP2.
A number of PRRs can be secreted by cells, and bind directly to invading micro-organisms. Some examples of these proteins are collectins, pentraxins, ficolins, lipid transferases, peptidoglycan recognition proteins (PGRs) and the leucine-rich repeat receptor (LRR).
Key Pattern Recognition Receptor Markers
Bio-Rad offers a large range of antibodies to these main types of pattern recognition receptors and to their signaling and effector molecules. Browse our range below.
Pattern Recognition Receptor Antibodies