Co-operative nature of N-glycosylation of proteins at multiple sites: evidence from studies with tunicamycin.
The pattern of glycosylation of newly synthesized human and murine immunoglobulin mu-chains varies according to the degree of inhibition of N-glycosylation effected by using the antibiotic tunicamycin. Tunicamycin, at high concentrations, can apparently block N-glycosylation of mu-chains completely as judged by SDS-PAGE analysis of the biosynthetically labelled products. At lower concentrations of tunicamycin, fully glycosylated and totally non-glycosylated chains were the predominant molecular species. The paucity of the predicted partially glycosylated mu-chains leads us to suggest that the addition of oligosaccharides to the appropriate acceptor sites is a cooperative process. Long exposure of fluorographs reveals each of the predicted intermediately glycosylated forms of the mu-chain, and counting the number of bands on such fluorographs may prove useful in the preliminary determination of the number of N-linked oligosaccharides in a given glycoprotein.
D000818:Animals; D050260:Carbohydrate Metabolism; D002460:Cell Line; D005944:Glucosamine / Q000031:analogs & derivatives*; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000096:biosynthesis*; D007148:Immunoglobulin mu-Chains / Q000096:biosynthesis*; D008223:Lymphoma / Q000378:metabolism; D051379:Mice; D010954:Plasmacytoma / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D014415:Tunicamycin / Q000494:pharmacology*
D007143:Immunoglobulin Heavy Chains; D007148:Immunoglobulin mu-Chains; D014415:Tunicamycin; D005944:Glucosamine