title: Collectins: players of the innate immune system.
abstract: Collectins are a family of collagenous calcium-dependent defense lectins in animals. Their polypeptide chains consist of four regions: a cysteine-rich N-terminal domain, a collagen-like region, an alpha-helical coiled-coil neck domain and a C-terminal lectin or carbohydrate-recognition domain. These polypeptide chains form trimers that may assemble into larger oligomers. The best studied family members are the mannan-binding lectin, which is secreted into the blood by the liver, and the surfactant proteins A and D, which are secreted into the pulmonary alveolar and airway lining fluid. The collectins represent an important group of pattern recognition molecules, which bind to oligosaccharide structures and/or lipid moities on the surface of microorganisms. They bind preferentially to monosaccharide units of the mannose type, which present two vicinal hydroxyl groups in an equatorial position. High-affinity interactions between collectins and microorganisms depend, on the one hand, on the high density of the carbohydrate ligands on the microbial surface, and on the other, on the degree of oligomerization of the collectin. Apart from binding to microorganisms, the collectins can interact with receptors on host cells. Binding of collectins to microorganisms may facilitate microbial clearance through aggregation, complement activation, opsonization and activation of phagocytosis, and inhibition of microbial growth. In addition, the collectins can modulate inflammatory and allergic responses, affect apoptotic cell clearance and modulate the adaptive immune system.
authors.affiliation: Department of Biochemistry and Cell Biology, Graduate School of Animal Health, Faculty of Veterinary Medicine, Utrecht University, the Netherlands.
authors.forename: J Koenraad
authors.initials: JK
authors.lastname: van de Wetering
authors.forename: Lambert M G
authors.initials: LM
authors.lastname: van Golde
authors.forename: Joseph J
authors.initials: JJ
authors.lastname: Batenburg
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry; D002241:Carbohydrates / Q000737:chemistry; D037222:Collectins / Q000737:chemistry* / Q000502:physiology*; D000939:Epitopes / Q000737:chemistry; D005656:Fungal Proteins / Q000737:chemistry; D006801:Humans; D007107:Immune System / Q000502:physiology*; D007249:Inflammation; D008055:Lipids / Q000737:chemistry; D008954:Models, Biological; D009005:Monosaccharides / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D014764:Viral Proteins / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D002241:Carbohydrates; D037222:Collectins; D000939:Epitopes; D005656:Fungal Proteins; D008055:Lipids; D009005:Monosaccharides; D011134:Polysaccharides; D014764:Viral Proteins