title: Characterization of the N-linked oligosaccharides of megalin (gp330) from rat kidney.
abstract: Megalin (gp 330) is a large cell surface receptor expressed on the apical surfaces of epithelial tissues, that mediates the binding and internalization of a number of structurally and functionally distinct ligands. In this paper we report the first detailed structural characterization of megalin-derived oligosaccharides. Using strategies based on mass spectrometric analysis, we have defined the structures of the N-glycans of megalin. The results reveal that megalin glycoprotein is heterogeneously glycosylated. The major N-glycans identified belong to the following two classes: high mannose structures and complex type structures, with complex structures being more abundant than high mannose structures. The major nonreducing epitopes in the complex-type glycans are: GlcNAc, Galbeta1-4GlcNAc (LacNAc), NeuAcalpha2-6Galbeta1-4GlcNAc (sialylated LacNAc), GalNAcbeta1-4[NeuAcalpha2-3]Galbeta1-4GlcNAc (Sd(a)) and Galalpha1-3Galbeta1-4GlcNAc. Most complex structures are characterized by the presence of (alpha1,6)-core fucosylation and the presence of a bisecting GlcNAc residue.
authors.affiliation: Department of Biochemistry, Imperial College, London, SW7 2AY, UK.
authors.forename: W
authors.initials: W
authors.lastname: Morelle
authors.forename: S M
authors.initials: SM
authors.lastname: Haslam
authors.forename: M
authors.initials: M
authors.lastname: Ziak
authors.forename: J
authors.initials: J
authors.lastname: Roth
authors.forename: H R
authors.initials: HR
authors.lastname: Morris
authors.forename: A
authors.initials: A
authors.lastname: Dell
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D006026:Glycoside Hydrolases / Q000378:metabolism; D006031:Glycosylation; D026541:Heymann Nephritis Antigenic Complex; D007668:Kidney / Q000737:chemistry* / Q000378:metabolism; D013058:Mass Spectrometry; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D009005:Monosaccharides / Q000737:chemistry; D009844:Oligosaccharides / Q000737:chemistry*; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D011134:Polysaccharides / Q000737:chemistry; D051381:Rats; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D026541:Heymann Nephritis Antigenic Complex; D008562:Membrane Glycoproteins; D009005:Monosaccharides; D009844:Oligosaccharides; D011134:Polysaccharides; D006026:Glycoside Hydrolases; C026093:keratan-sulfate endo-1,4-beta-galactosidase; D001616:beta-Galactosidase; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase