Temporal aspects of O-glycosylation of glycoprotein C from herpes simplex virus type-1.
Herpes simplex virus type-1 glycoprotein C (gC1) contains several O-linked oligosaccharides clustered near N-linked chains, and Pronase digestion produces glycopeptides carrying both oligosaccharide types. We have taken advantage of this fact to investigate the temporal relationship between the initiation of O-linked chains and the processing of N-linked oligosaccharides. gC1 was isolated from herpes-simplex-virus-infected BHK (baby-hamster kidney) cells after short labelling periods with [3H]glucosamine, and the labelled Pronase-cleaved glycopeptides fractionated on concanavalin A-Sepharose. N-[3H]Acetylgalactosamine, mostly convertible into free N-[3H]acetylgalactosaminitol on mild alkaline-borohydride treatment, was found in glycopeptides with an affinity to concanavalin A-Sepharose corresponding to that of glycopeptides carrying Man8GlcNAc2 or larger N-linked chains. Since there is evidence that the processing of N-linked chains up to Man8GlcNAc2 involves enzymes located in the rough endoplasmic reticulum, current results strongly suggest that gC1 acquires O-linked N-acetylgalactosamine before the glycoprotein routing to the Golgi apparatus. The addition of the second sugar to the nascent O-linked chain appeared to occur after a relatively long lag time.
Serafini-Cessi
F
F
Dipartimento di Patologia Sperimentale, Università di Bologna, Italy.
Dall'Olio
F
F
Malagolini
N
N
Campadelli-Fiume
G
G
D000116:Acetylgalactosamine / Q000378:metabolism; D006020:Glycopeptides / Q000378:metabolism; D006031:Glycosylation; D011402:Pronase; D018139:Simplexvirus / Q000378:metabolism*; D013997:Time Factors; D014759:Viral Envelope Proteins / Q000378:metabolism*
D006020:Glycopeptides; D014759:Viral Envelope Proteins; C038535:glycoprotein gC, herpes simplex virus type 1; D011402:Pronase; D000116:Acetylgalactosamine