title: Effect of tunicamycin and monensin on the transport to the cell surface and secretion of a viral membrane glycoprotein containing both N- and O-linked sugars.
abstract: Most membrane glycoproteins contain either N-linked or O-linked oligosaccharides, which play important roles in correct folding, stability, and intracellular transport. Some glycoproteins, however, contain both the N- and O-linked sugars. To study the roles of the two types of glycosylation in intracellular transport we have used as a model the glycoprotein gC-1 of herpes simplex virus type 1 (HSV-1), which contains both N- and O-linked oligosaccharides. Cloned gene of gC-1 was expressed constitutively in mammalian cells to produce the gC-1 glycoprotein containing both types of glycosylation. Only a fraction of the gC-1 glycoprotein was secreted into the medium. Addition of tunicamycin blocked N-glycosylation and the gC-1 protein of reduced size containing only O-linked sugars was formed. This O-glycosylated gC-1 protein was transported to the cell surface and secreted into the medium, indicating that glycoprotein transport to and across the cell surface occurs in the absence of N-glycans. The data suggest either that O-glycans may contribute to this process or that transport can occur in the absence of both N- and O-glycans.
authors.affiliation: McMaster University, Department of Biochemistry, Hamilton, ON, Canada.
authors.forename: N
authors.initials: N
authors.lastname: Ghosh-Choudhury
authors.forename: M
authors.initials: M
authors.lastname: Butcher
authors.forename: E
authors.initials: E
authors.lastname: Reid
authors.forename: H P
authors.initials: HP
authors.lastname: Ghosh
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D016466:CHO Cells; D002236:Carbohydrate Conformation; D002460:Cell Line; D006224:Cricetinae; D006031:Glycosylation; D007700:Kinetics; D008985:Monensin / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000378:metabolism; D018139:Simplexvirus; D014162:Transfection; D014415:Tunicamycin / Q000494:pharmacology*; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D011994:Recombinant Proteins; D014759:Viral Envelope Proteins; C038535:glycoprotein gC, herpes simplex virus type 1; D014415:Tunicamycin; D008985:Monensin