scholarly journals Different effects of the glucosidase inhibitors 1-deoxynojirimycin, N-methyl-1-deoxynojirimycin and castanospermine on the glycosylation of rat α1-proteinase inhibitor and α1-acid glycoprotein

1986 ◽  
Vol 236 (3) ◽  
pp. 853-860 ◽  
Author(s):  
V Gross ◽  
T A Tran-Thi ◽  
R T Schwarz ◽  
A D Elbein ◽  
K Decker ◽  
...  
Keyword(s):  
Proteinase Inhibitor ◽  
De Novo ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Complex Type ◽  
Glucose Residue ◽  
Acid Glycoprotein ◽  
Glucosidase Inhibitors ◽  
Oligosaccharide Processing ◽  
High Mannose

The glucosidase inhibitors 1-deoxynojirimycin, N-methyl-1-deoxynojirimycin and castanospermine were used to inhibit oligosaccharide processing in primary cultures of rat hepatocytes. Their effect on the glycosylation of alpha 1-proteinase inhibitor (alpha 1PI) and alpha 1-acid glycoprotein (alpha 1AGP) was studied. Of the three glucosidase inhibitors examined, 1-deoxynojirimycin inhibited not only oligosaccharide trimming but also glycosylation de novo of newly synthesized proteins, resulting in the formation of alpha 1PI with two and three (normally carrying three) and alpha 1AGP with two to five (normally carrying six) oligosaccharide side chains. In the presence of the glucosidase inhibitors, glucosylated high-mannose-type oligosaccharides accumulated. Whereas most of the endoglucosaminidase-H-sensitive oligosaccharides formed in the presence of 1-deoxynojirimycin contained only one glucose residue, N-methyl-1-deoxynojirimycin and castanospermine led mainly to the formation of oligosaccharides with three glucose residues. None of the three glucosidase inhibitors completely prevented the formation of complex-type oligosaccharides. Thus, in their presence, alpha 1PI and alpha 1AGP with a mixture of both high-mannose and complex-type oligosaccharides were secreted.

Effects of insulin, dexamethasone and cytokines on ?1-acid glycoprotein gene expression in primary cultures of normal rat hepatocytes

Inflammation ◽  
1996 ◽  
Vol 20 (2) ◽  
pp. 191-202 ◽  
Author(s):  
B�atrice Barraud ◽  
Sophie Balavoine ◽  
G�rard Feldmann ◽  
Bernard Lardeux
Keyword(s):  
Gene Expression ◽  
Primary Cultures ◽  
Rat Hepatocytes ◽  
Acid Glycoprotein ◽  
Glycoprotein Gene ◽  
Normal Rat

scholarly journals Carbohydrate structures of the third component of rat complement Presence of both high-mannose and complex type oligosaccharide chains

1986 ◽  
Vol 240 (3) ◽  
pp. 691-698 ◽  
Author(s):  
K Miki ◽  
S Ogata ◽  
Y Misumi ◽  
Y Ikehara
Keyword(s):  
High Performance ◽  
Gel Filtration ◽  
Rat Hepatocytes ◽  
Alpha Subunit ◽  
Complement C3 ◽  
Complex Type ◽  
Rat Serum ◽  
The Third ◽  
High Mannose ◽  
Fraction I

We investigated the carbohydrate structure of the third component of complement (C3) newly synthesized by cultured rat hepatocytes. When the cells were incubated with [3H]mannose, [3H]galactose or [3H]glucosamine, these radioactive precursors were incorporated only into the alpha subunit of C3, demonstrating that only the alpha subunit contains oligosaccharide chains. [3H]Mannose-labelled C3 was purified from the culture medium by immunoaffinity chromatography. Oligosaccharides prepared by Pronase digestion and strong alkaline hydrolysis were separated into two fractions by Bio-Gel P-2 chromatography (Fractions I and II). The two fractions were analysed by concanavalin A-Sepharose chromatography, ion-exchange high-performance liquid chromatography, and Bio-Gel P-4 gel filtration before and after sequential exoglycosidase digestions. It was found that Fraction I contained two complex type oligosaccharide chains, (NeuAc)2(Gal)2(GlcNAc)2(Man)3(GlcNAc)2 and (NeuAc)3(Gal)3(GlcNAc)3(Man)3(GlcNAc)2, and Fraction II contained the high-mannose type, consisting mainly of (Man)8(GlcNAc)2. Taken together with the carbohydrate composition of rat serum C3, the results suggest that rat C3 has one high-mannose type oligosaccharide chain and two complex type chains in the alpha subunit, which is different from the proposal for human C3.

scholarly journals Processing of MOPC 315 immunoglobulin A oligosaccharides: evidence for endoplasmic reticulum and trans Golgi alpha 1,2-mannosidase activity.

1984 ◽  
Vol 98 (2) ◽  
pp. 407-416 ◽  
Author(s):  
S Hickman ◽  
J L Theodorakis ◽  
J M Greco ◽  
P H Brown
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Complex ◽  
Immunoglobulin A ◽  
Complex Type ◽  
Mannose Residue ◽  
Alpha Chain ◽  
Oligosaccharide Processing ◽  
Carbonyl Cyanide ◽  
High Mannose ◽  
Initial Processing

The processing of asparagine-linked oligosaccharides on the alpha-chains of an immunoglobulin A (IgA) has been investigated using MOPC 315 murine plasmacytoma cells. These cells secrete IgA containing complex-type oligosaccharides that were not sensitive to endo-beta-N-acetylglucosaminidase H. In contrast, oligosaccharides present on the intracellular alpha-chain precursor were of the high mannose-type, remaining sensitive to endo-beta-N-acetylglucosaminidase H despite a long intracellular half-life of 2-3 h. The major [3H]mannose-labeled alpha-chain oligosaccharides identified after a 20-min pulse were Man8GlcNAc2 and Man9GlcNAc2. Following chase incubations, the major oligosaccharide accumulating intracellularly was Man6GlcNAc2, which was shown to contain a single alpha 1,2-linked mannose residue. Conversion of Man6GlcNAc2 to complex-type oligosaccharides occurred at the time of secretion since appreciable amounts of Man5GlcNAc2 or further processed structures could not be detected intracellularly. The subcellular locations of the alpha 1,2-mannosidase activities were studied using carbonyl cyanide m-chlorophenylhydrazone and monensin. Despite inhibiting the secretion of IgA, these inhibitors of protein migration did not effect the initial processing of Man9GlcNAc2 to Man6GlcNAc2. Furthermore, no large accumulation of Man5GlcNAc2 occurred, indicating the presence of two subcellular locations of alpha 1,2-mannosidase activity involved in oligosaccharide processing in MOPC 315 cells. Thus, the first three alpha 1,2-linked mannose residues were removed shortly after the alpha-chain was glycosylated, most likely in rough endoplasmic reticulum, since this processing occurred in the presence of carbonyl cyanide m-chlorophenylhydrazone. However, the removal of the final alpha 1,2-linked mannose residue as well as subsequent carbohydrate processing occurred just before IgA secretion, most likely in the trans Golgi complex since processing of Man6GlcNAc2 to Man5GlcNAc2 was greatly inhibited in the presence of monensin.

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