Re-expression of nonglycosylated surface IgA in trypsin-treated MOPC 315 plasmacytoma cells.
The importance of glycosylation for the re-expression of surface immunoglobulin in trypsin-treated MOPC 315 plasmacytoma cells was examined by using tunicamycin, an antibiotic that prevents glycosylation by inhibiting the formation of N-acetylglucosamine-lipid intermediates. Tunicamycin greatly inhibited the secretion of nonglycosylated MOPC 315 IgA in trypsin-treated cells. Two hours after trypsin treatment, there was an 80% inhibition of secretion as measured by immunoprecipitation assays of biosynthetically labeled immunoglobulin. However, tunicamycin had no effect on the time course of re-expression of surface IgA in these cells as measured by TNP-sheep erythrocyte rosette formation and [125I] TNP-albumin binding to the plasmacytoma cells. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of 125I-labeled cell surface IgA re-expressed in the presence of tunicamycin revealed a protein with an apparent m.w. identical to nonglycosylated MOPC 315 alpha-chains, further suggesting that nonglycosylated surface IgA was being inserted into the plasma membrane. This protein did not bind to concanavalin A-Sepharose. These data suggest that in MOPC 315 plasmacytoma cells, glycosylation is necessary for immunoglobulin secretion but not for immunoglobulin expression at the cell surface.
D000818:Animals; D001665:Binding Sites; D002417:Cattle; D007070:Immunoglobulin A / Q000378:metabolism; D007784:Lactoperoxidase / Q000378:metabolism; D051379:Mice; D010954:Plasmacytoma / Q000276:immunology*; D011947:Receptors, Antigen, B-Cell; D012397:Rosette Formation; D012710:Serum Albumin, Bovine / Q000276:immunology; D012756:Sheep; D013997:Time Factors; D014301:Trinitrobenzenes / Q000276:immunology; D014357:Trypsin / Q000494:pharmacology*; D014415:Tunicamycin / Q000494:pharmacology
D007070:Immunoglobulin A; D011947:Receptors, Antigen, B-Cell; D014301:Trinitrobenzenes; D014415:Tunicamycin; D012710:Serum Albumin, Bovine; D007784:Lactoperoxidase; D014357:Trypsin