- Collectin
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Collectins are soluble pattern recognition receptors (PRRs) belonging to the superfamily of collagen containing C-type lectins.
Eight collectins have been identified including mannan-binding lectin (MBL), surfactant protein A (SP-A), surfactant protein D (SP-D), collectin liver 1 (CL-L1), collectin placenta 1 (CL-P1), conglutinin, collectin of 43 kDa (CL-43) and collectin of 46 kDa (CL-46).
These molecules have been implicated as major modulators of the innate immune system where they have a key role in the first line of defense against invading microorganisms by binding to them so macrophages know to dispose of them.[1]
Functionally, collectins are usually trimers with the number of trimeric units differing among the collectin family.Structural domains
The collectin monomers comprise four structural domains;
- a cysteine-rich domain at the N-terminus.
- a collagen domain.
- a coiled-coil neck domain .
- a C-type lectin domain that is also called a carbohydrate recognition domain (CRD). Collectins selectively bind to specific complex carbohydrates of microbes using their CRDs.[2]
Responses
The binding of collectins to microbes causes several immune related responses.
- They cause the formation of aggregates of the microorganisms, opsonize the microorganisms to increase their phagocytosis and some upregulate of the activity of other PRRs such as the mannose receptor.
- Collectins can also induce the production of pro-inflammatory molecules like cytokines, and reactive oxygen species in phagocytes by interacting with other cell surface receptors or by scavenging of bacterial molecules like lipopolysaccharide (LPS).
- Some collectins (e.g. MBL) activate the lectin pathway of the complement system to increase membrane permeability of microorganisms and cause the destruction of that microbe.[2]
References
- ^ http://www.jimmunol.org/cgi/content/full/169/10/5726
- ^ a b van de Wetering et al. Collectins: Players of the innate immune system. Eur. J. Biochem. 271, 1229-1249 (2004)
Animal C-type lectinsAsialoglycoprotein receptor · KLRD1 · Collectin (Mannan-binding lectin) · Mannose receptor · proteochondroitin sulfate (Aggrecan, Versican, Brevican, Neurocan)OtherPlant Abrin · Ricin · Mitogens (Concanavalin A, Phytohaemagglutinin, Pokeweed mitogen) · Legume lectin · BanLecMembrane-bound_PRRs Cytoplasmic_PRRs Secreted_PRRs Other/ungrouped Categories:- Lectins
- Immunology stubs
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