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Am J Respir Cell Mol Biol. 2002 Jun;26(6):739-47.

Porcine surfactant protein D is N-glycosylated in its carbohydrate recognition domain and is assembled into differently charged oligomers.

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  • 1Department of Biochemistry and Cell Biology, Graduate School of Animal Health, Faculty of Veterinary Medicine, Utrecht University, The Netherlands. m.vaneijk@vet.uu.nl

Abstract

Surfactant protein D (SP-D) belongs to a subgroup of mammalian collagenous Ca(2+)-dependent lectins known as the collectins. It is thought to play a significant role in the innate immune response against microorganisms within the lungs and at other mucosal surfaces. This report documents the isolation and characterization of SP-D purified from porcine lung lavage using mannan affinity chromatography and gel filtration. Ultrastructural analysis shows both dodecameric and higher order oligomeric complexes of SP-D. The molecular mass of monomeric porcine SP-D (50 kD) is larger than that of SP-D from humans (43 kD). The difference in mass is due to the presence of an Asparagine-linked glycosylation in the carbohydrate recognition domain of porcine SP-D, which is absent in SP-D of other species investigated so far. Analysis of this carbohydrate moiety indicates that it is a highly heterogeneous, complex type oligosaccharide which is sialylated. The heterogeneity of oligosaccharide sialylation results in the existence of many differently charged porcine SP-D isoforms. The removal of the carbohydrate moiety reduces the inhibitory effect of porcine SP-D on influenza A virus haemagglutination. Therefore, the carbohydrate moiety may influence interactions with pathogens.

PMID:
12034574
[PubMed - indexed for MEDLINE]
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