Stimulation of the biosynthesis of lactosamine repeats in glycoproteins in differentiating U937 cells and its suppression in the presence of NH4Cl
| Autor: | J, Radons, V, Faber, H, Buhrmester, W, Völker, V, Horejsí, A, Hasilik |
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| Rok vydání: | 1992 |
| Předmět: |
Membrane Glycoproteins
Molecular Sequence Data Antibodies Monoclonal Lysosome-Associated Membrane Glycoproteins Amino Sugars Cell Differentiation N-Acetylglucosaminyltransferases Ammonium Chloride Calcitriol Antigens CD Glucosyltransferases Tumor Cells Cultured Animals Humans Amino Acid Sequence Repetitive Sequences Nucleic Acid |
| Zdroj: | European journal of cell biology. 57(2) |
| ISSN: | 0171-9335 |
| Popis: | We prepared a mouse monoclonal antibody, 2D5, which recognized a highly glycosylated human lysosomal membrane antigen. The apparent molecular mass of this antigen was cell type dependent and ranged between 100 kDa and 130 kDa. The difference was due to a variation in the carbohydrate moiety, since upon removal of the N-linked oligosaccharides the size of the glycoprotein was reduced to approximately 50 kDa in all cases. The high carbohydrate contents, subcellular localization and N-terminal sequence indicated a high similarity or identity of this antigen with the lamp-2 protein. In U937 cells several agents known to elicit differentiation induced synthesis of a larger form of the lamp antigen. Thus, treatment of cells with calcitriol resulted in a shift in its average molecular mass from 115 kDa to 130 kDa. The difference was due to an increase in the contents of lactosamine repeats. In subcellular membranes from calcitriol-treated cells the specific activity of the UDP-N-acetylglucosamine: N-acetyllactosamine N-acetylglucosaminyltransferase was enhanced 3-fold. The enhancement was accompanied with an elongation of lactosamine repeats in N-linked oligosaccharides in the 46 kDa mannose 6-phosphate receptor and the homing receptor, the leucocyte antigen CD44. In contrast, the apparent size of the leucocyte antigen CD43 which bears numerous O-linked oligosaccharides was not changed indicating a selectivity in the modulation of the formation of lactosamine repeats in N- and O-linked carbohydrates. It is shown further that the synthesis of lactosamine repeats in U937 cells is impeded in the presence of NH4Cl. |
| Databáze: | OpenAIRE |
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