title: Effect of tunicamycin on the biosynthesis of the major human red cell sialoglycoprotein, glycophorin A, in the leukemia cell line K562.
abstract: The human continuous leukemia cell line K562 synthesizes and expresses on its surface the major red cell sialoglycoprotein, glycophorin A. Glycophorin A contains 1 N-glycosidic and 15 O-glycosidic oligosaccharides, which are attached to known sites on the polypeptide chain. By immune precipitation with specific anti-glycophorin A antiserum of radioactively labeled cells followed by polyacrylamide gel electrophoresis, we have been able to study its biosynthesis in considerable detail. The synthesis of the N-glycosidic oligosaccharide of glycophorin A is inhibited by the antibiotic tunicamycin, while the O-glycosidic oligosaccharides are not affected. Incomplete glycophorin A, lacking the N-glycosidic oligosaccharide, is apparently incorporated normally into the surface membrane, but the total amount of glycophorin A is decreased. Thus, N-glycosylation is not necessary for externalization of glycophorin A.
mesh_terms: D002460:Cell Line; D005690:Galactose / Q000378:metabolism; D005944:Glucosamine / Q000031:analogs & derivatives* / Q000378:metabolism; D006021:Glycophorins / Q000096:biosynthesis*; D006801:Humans; D007700:Kinetics; D007938:Leukemia; D008715:Methionine / Q000378:metabolism; D012795:Sialoglycoproteins / Q000096:biosynthesis*; D014415:Tunicamycin / Q000494:pharmacology*
chemical_list: D006021:Glycophorins; D012795:Sialoglycoproteins; D014415:Tunicamycin; D008715:Methionine; D005944:Glucosamine; D005690:Galactose