title: Retention of glucose on oligosaccharide chains linked to the LH/hCG receptor prevents cell surface expression.
abstract: In the first step of asparagine-linked oligosaccharide chain maturation, terminal glucose residues are removed from the high mannose oligosaccharide core by glucosidases I and II. The role that glucose residues play in trafficking the luteinizing hormone/human chorionic gonadotropin (LH/hCG) receptor from the endoplasmic reticulum to the cell surface was investigated. Glucosidases I and II were inhibited by incubating 293 T cells transiently transfected with LH/hCG receptor cDNA with 5 mM 1-deoxynojirimycin (DNJ). DNJ treatment resulted in a marked reduction in cell surface [(125)I]hCG binding. Similar results were obtained from glucosidase I-deficient Lec 23 Chinese hamster ovarian (CHO) cells and wild-type CHO cells that were transiently transfected with LH/hCG receptor cDNA. Immunoprecipitation followed by Western blotting of transfected 293 T cells incubated in the presence or absence of 5 mM DNJ revealed that there is substantially less receptor in DNJ-treated cells than in control cells. These results show that the removal of glucose residues is necessary for trafficking the LH/hCG receptor to the cell surface.
authors.affiliation: Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan, 48109-0617, USA.
authors.forename: F A
authors.initials: FA
authors.lastname: Bradbury
authors.forename: K M
authors.initials: KM
authors.lastname: Menon
mesh_terms: D017485:1-Deoxynojirimycin / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D001693:Biological Transport, Active; D016466:CHO Cells; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D006224:Cricetinae; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005947:Glucose / Q000737:chemistry*; D065089:Glycoside Hydrolase Inhibitors; D006801:Humans; D009844:Oligosaccharides / Q000737:chemistry* / Q000378:metabolism*; D011974:Receptors, LH / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D000520:alpha-Glucosidases / Q000378:metabolism
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; D009844:Oligosaccharides; D011974:Receptors, LH; D017485:1-Deoxynojirimycin; D000520:alpha-Glucosidases; D005947:Glucose