Difference in binding-site architecture of the serum-type and liver-type mannose-binding proteins.
The carbohydrate-recognition domains (CRDs) of the serum-type and the liver-type mannose-binding proteins (MBPs) from rat display different binding characteristics toward mannose-rich oligosaccharides derived from N-glycosides, despite the overall similarity in their binding site architecture, oligomeric status and actual binding specificity at the monosaccharide level. We found that the liver-type MBP CRD of rat (MBP-C) bound methyl glycosides of certain mannobioses and -trioses, which are part of the mannose-rich N-glycoside, more tightly than methyl alpha-mannopyranoside. In contrast, the serum-type MBP CRD of rat (MBP-A) bound all the methyl glycosides of manno-oligosaccharide and methyl alpha-mannopyranoside with similar affinities. The mannobiose and -triose most strongly bound to MBP-C CRD were Man alpha (1-2)Man alpha-OMe and Man alpha (1-2)Man alpha (1-6)Man alpha-OMe, respectively. From these and other data, we postulate that the binding site of MBP-C has an extended area of interaction, probably the size of a mannotriose, while MBP-A interacts essentially with one mannose residue.
Lee
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RT
Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
Lee
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YC
D000818:Animals; D001665:Binding Sites; D002240:Carbohydrate Sequence; D002352:Carrier Proteins / Q000097:blood / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008358:Mannose; D037241:Mannose-Binding Lectins; D008362:Mannosides; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis; D051381:Rats; D013379:Substrate Specificity
D002352:Carrier Proteins; D046911:Macromolecular Substances; D037241:Mannose-Binding Lectins; D008362:Mannosides; D009844:Oligosaccharides; D008358:Mannose