tailieunhanh - Báo cáo khoa học: Characterization of mucin-type core-1 b1-3 galactosyltransferase homologous enzymes in Drosophila melanogaster

Mucin type O-glycosylation is a widespread modification of eukaryotic pro-teins. The transfer of N-acetylgalactosamine to selected serine or threonine residues is catalyzed by a family of polypeptide N-acetylgalactosaminyl-transferases localized in the Golgi apparatus. The most abundant elonga-tion of O-glycans is the addition of a b1-3 linked galactose by the core-1 b1-3 galactosyltransferase (core-1b3GalT), thereby building the T-antigen or core-1 structure Gal(b1-3)GalNAc(a1-O). | ềFEBS Journal Characterization of mucin-type core-1 01-3 galactosyltransferase homologous enzymes in Drosophila melanogaster Reto Muller1 Andreas J Hulsmeier1 Friedrich Altmann2 Kelly Ten Hagen3 Michael Tiemeyer4 and Thierry Hennet1 1 Institute of Physiology University of Zurich Switzerland 2 Institute of Chemistry Universitat fur Bodenkultur Wien Austria 3 DevelopmentalGlycobiology Unit Nationallnstitute of Dentaland CraniofacialResearch Nationallnstitutes of Health Bethesda MD USA 4 Complex Carbohydrate Research Center The University of Georgia Athens GA USA Keywords Drosophila galactosyltransferase glycolipid glycosylation mucin Correspondence T. Hennet University of Zurich Institute of Physiology Winterthurerstrasse 190 8057 Zurich Switzerland Fax 41 44 6356814 E-mail thennet@ Received 22 March 2005 revised 11 June 2005 accepted 29 June 2005 doi Mucin type O-glycosylation is a widespread modification of eukaryotic proteins. The transfer of N-acetylgalactosamine to selected serine or threonine residues is catalyzed by a family of polypeptide N-acetylgalactosaminyl-transferases localized in the Golgi apparatus. The most abundant elongation of O-glycans is the addition of a P1-3 linked galactose by the core-1 P1-3 galactosyltransferase core-1 b3GalT thereby building the T-antigen or core-1 structure Gal b1-3 GalNAc a1-O . We have isolated four Drosophila melanogaster cDNAs encoding proteins structurally similar to the human core-1 b3GalT enzyme and expressed them as FLAG-tagged proteins in Sf9 insect cells. The identity of these D. melanogaster b3GalT enzymes with a core-1 b3GalT activity was confirmed by utilization of MUC5AC mucin derived O-glycopeptide acceptors. In addition to the core-1 b3GalT activity toward O-glycoprotein substrates one member of this enzyme family showed a strong activity towards glycolipid acceptors thereby building the core-1 terminated Nz6 glycosphingolipid. Transcripts of the .