title: Distance of sequons to the C-terminus influences the cellular N-glycosylation of the prion protein.
abstract: Cell-specific differences in the utilization of the two N-glycosylation sequons (Asn180-Ile-Thr and Asn196-Phe-Thr) of the prion protein (PrP) have been proposed to influence the aetiology of the neurodegenerative prion diseases. As the N-glycosylation of PrP is ablated by deletion of the C-terminal glycosyl-phosphatidylinositol (GPI) anchor signal sequence, we have investigated the determinants for PrP sequon utilization in human neuronal cells using the novel approach of restoring N-glycosylation to secreted forms of PrP lacking a GPI anchor. N-glycosylation was restored to an efficiency comparable with that of GPI anchored PrP when the distance of the sequon to the C-terminus was increased so that it was sufficient to reach the active site of oligosaccharyltransferase before chain termination. Our findings indicate that sequon utilization in PrP is a co-translational process that precedes GPI anchor addition and, as such, will be greatly influenced by the dynamics of the translocon-oligosaccharyltransferase complex.
authors.affiliation: School of Biochemistry and Molecular Biology, University of Leeds, Leeds LS2 9JT, U.K.
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Walmsley
authors.forename: Nigel M
authors.initials: NM
authors.lastname: Hooper
mesh_terms: D000581:Amidohydrolases / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D006031:Glycosylation; D006801:Humans; D006868:Hydrolysis; D051379:Mice; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D011328:Prions / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D017931:DNA Primers; D011328:Prions; D010738:Type C Phospholipases; D000581:Amidohydrolases; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase; D043265:Phosphatidylinositol Diacylglycerol-Lyase