title: Glycosylation of the human erythrocyte glucose transporter: a minimum structure is required for glucose transport activity.
abstract: The involvement of the carbohydrate moiety of the human erythrocyte glucose transporter in glucose transport activity was previously demonstrated (Feugeas et al. (1990) Biochim. Biophys. Acta 1030, 60-64): N-glycanase treatment of the transport glycoprotein reconstituted in proteoliposomes resulted in a dramatic decrease of the Vmax. In this study, kinetic measurements of glucose equilibrium influx confirm our previous results. In order to investigate that a minimum glycosidic structure is required to maintain glucose transport activity, proteoliposomes were respectively treated with either sialidase, or sialidase and endo-beta-galactosidase, or a pool of exo-glycosidases which allows the release of all the sugar residues, except the proximal N-acetylglucosamine. Kinetic measurements of zero-trans influx made on sialidase- and (sialidase + endo-beta-galactosidase)-treated proteoliposomes did not reveal any significant changes in the glucose transport activity. On the contrary, treatment of the same proteoliposomes by a pool of exoglycosidases led to a complete abolition of activity, suggesting that a minimum glycosidic structure is required for glucose transport activity.
authors.affiliation: INSERM U180, UFR Biomédicale, Paris, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Feugeas
authors.forename: D
authors.initials: D
authors.lastname: Néel
authors.forename: Y
authors.initials: Y
authors.lastname: Goussault
authors.forename: C
authors.initials: C
authors.lastname: Derappe
mesh_terms: D001692:Biological Transport; D002240:Carbohydrate Sequence; D004912:Erythrocytes / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000378:metabolism* / Q000648:ultrastructure; D011510:Proteolipids / Q000378:metabolism
chemical_list: D009004:Monosaccharide Transport Proteins; D011510:Proteolipids; C020485:proteoliposomes; D006026:Glycoside Hydrolases; C020668:glycanase; D005947:Glucose