Collectins

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 α‐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.

Plasma proteome of severe acute respiratory syndrome analyzed by two-dimensional gel electrophoresis and mass spectrometry

“…It is a member of the C-type lectin family closely associated with infectious diseases (22) and host defense (23) against pathogens, such as influenza A virus (24) and HIV (25). The lectin complement pathway is activated upon pathogen exposure to promote chemotactaxis, cytolysis, and inflammation (26). Activation of the complement system in SARS could also be facilitated by the overexpressed complement C4 and C3 fragments and complement factor H-related protein 1 found in this study.…”

CD40L-Adjuvanted DNA/Modified Vaccinia Virus Ankara Simian Immunodeficiency Virus SIV239 Vaccine Enhances SIV-Specific Humoral and Cellular Immunity and Improves Protection against a Heterologous SIVE660 Mucosal Challenge

“…There is growing evidence demonstrating the need for multimerization of the trimeric ligands for their activation/adjuvant potential (18)(19)(20). Multimerization can be achieved by the membrane-bound form (upon ligation with CD40) or the soluble form fused with multimerization domains of proteins from C1q superfamily molecules (21,22) and collectin superfamily molecules (23)(24)(25)(26)(27)) that spontaneously multimerize into molecular structures with extended, trimeric, collagen-like arms. Indeed, a recent study demonstrated that HIV-1 Gag DNA vaccine expressing the 4-trimer form of CD40L (extracellular domain of mouse CD40L fused to the multimerization domain of pulmonary surfactant protein D) is more immunogenic than the soluble 1-trimer form in mice (28).…”

Identification of the Surfactant Protein A Receptor 210 as the Unconventional Myosin 18A

“…Insoluble SP-A was then dialyzed for 48 h against four changes of solubilization buffer (SB: 5 mM HEPES, pH 7.5, 0.02% azide). Insoluble protein was removed by centrifugation at 50,000 ϫ g. The supernatant was adjusted to 20 mM in CaCl 2 and 1 M in NaCl by addition of 0.5 M CaCl 2 and NaCl crystals to re-precipitate SP-A. SP-A was then collected at 20,000 ϫ g for 20 min and washed three times in 5 mM HEPES, pH 7.5, 20 mM CaCl 2 , 1 M NaCl.…”

“…Cell Culture-All cell lines were cultured in DMEM or RPMI supplemented with 10% fetal bovine serum and maintained in a humidified tissue culture incubator under an atmosphere of 95% air, 10% CO 2 for DMEM grown cells and 5% CO 2 for RPMI grown cells.…”