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Encyclopedia > Pattern recognition receptor

Pattern recognition receptors, or PRRs, are a class of cell surface receptors which are employed by the cells of the immune system to identify foreign (disease-associated) biomolecules in the body. Cells in culture, stained for keratin (red) and DNA (green) The cell is the structural and functional unit of all living organisms, sometimes called the building blocks of life. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific factor (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... The immune system is the organ system that protects an organism from outside biological influences. ...

PRRs function by binding specifically to small portions of pathogenic molecules, including lipopolysaccharides, peptidoglycans, certain proteins, double-stranded RNA, and a number of others. The specific molecular sequences identified by a given PRR are its PAMPs: pathogen-associated molecular patterns. A pathogen (literally birth of pain from the Greek παθογένεια) is a biological agent that can cause disease to its host. ... A lipopolysaccharide (LPS) is a large molecule that contains both lipid and a carbohydrate. ... Peptidoglycan, also known as murein, is a homogenous layer lying outside the plasma membrane in prokaryotes. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Ribonucleic acid (RNA) is a nucleic acid consisting of a string of covalently-bound nucleotides. ... Pathogen-associated molecular patterns, or PAMPs, are small molecular sequences consistently found on pathogens. ...

The toll-like receptors are a major class of PRRs. Toll-like receptors (TLRs) are primary transmembrane proteins of immune cells that serve as a key part of the innate immune system, which recognizes perpetual infectuous threats. ...

  Results from FactBites:
Toll-like Receptors Reviews (12168 words)
The discovery of the family of Toll receptors in species as diverse as DROSOPHILA and humans, and the recognition of their role in distinguishing molecular patterns that are common to microorganisms have led to a renewed appreciation of the innate immune system.
Upon recognition of microbes by innate immune cells such as macrophages and dendritic cells, diverse signaling pathways are activated that combine to define inflammatory responses that direct sterilization of the threat and/or orchestrate development of the adaptive immune response.
The interaction of the bacterial constituents with receptors on the surface of mononuclear cells is mainly responsible for the induction of proinflammatory mediators by the bacterial constituents.
Sandra Diebold :Contacts :King's College London (1161 words)
Since 1989 many pathogen-associated molecular patterns and their corresponding pattern recognition receptors were identified and some of the mechanisms of pattern recognition were unravelled.
The first pattern recognition receptors that were characterised all belong to the Toll-like receptor (TLR) family and it became evident that recognition of bacteria by these TLRs is largely directed toward detection of specific microbial glycolipid, peptidoglycan and protein structures.
Recognition of viral nucleic acids takes place in the endosomal compartment of cells that have taken up virus or material from virus infected cells and is mediated by TLRs, or in the cytoplasm of infected cells where these viral stimuli activate cytoplasmic pattern recognition receptors such as RIG-I, MDA5 and/or PKR.
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