title: Glucuronic acid can extend O-linked core 1 glycans, but it contributes only weakly to the negative surface charge of Drosophila melanogaster Schneider-2 cells.
abstract: Previous studies of the mucin-type O-glycome of the fruit fly Drosophila melanogaster have revealed a restricted pattern of neutral core-type glycans corresponding to the Tn-(GalNAcalpha) and the T-antigen (Galbeta1-3GalNAcalpha). In particular, no extension of the core 1 glycan with acidic sugars, like sialic acid, was detected. Here we report on the identification of an acidic O-linked trisaccharide expressed on secreted endogenous and recombinant glycoproteins of the embryonal hemocyte-like Drosophila Schneider-2 (S2) cell line. The glycan is composed of glucuronic acid, galactose and N-acetylgalactosamine and its structure was determined as GlcA1-3Gal1-3GalNAc. The O-linked trisaccharide resembles the peripheral structures of acidic D. melanogaster glycosphingolipids. Glucuronic acid may substitute for sialic acid in this organism, however its expression on the S2 cell surface may only marginally contribute to the negative surface charge as revealed by free-flow cell electrophoresis prior to and after beta-glucuronidase treatment of the cells.
authors.affiliation: Institute of Biochemistry II, Medical Faculty, University of Cologne, Joseph-Stelzmann-Str. 52, 50931 Köln, Germany.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Breloy
authors.forename: Tilo
authors.initials: T
authors.lastname: Schwientek
authors.forename: Stefan
authors.initials: S
authors.lastname: Lehr
authors.forename: Franz-Georg
authors.initials: FG
authors.lastname: Hanisch
mesh_terms: D000818:Animals; D002240:Carbohydrate Sequence; D002462:Cell Membrane / Q000737:chemistry; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000378:metabolism*; D020723:Glucuronic Acid / Q000737:chemistry*; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006031:Glycosylation; D008969:Molecular Sequence Data; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014312:Trisaccharides / Q000737:chemistry* / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D006023:Glycoproteins; D011993:Recombinant Fusion Proteins; D014312:Trisaccharides; C530211:glucuronosyl-1-3-galactopyranosyl-1-3-N-acetylgalactosamine; D020723:Glucuronic Acid