Glycosylation of gamma-glutamyltransferase is modified by ethanol in H5-6 hepatoma cell line.
The H5-6 cultured rat hepatoma cell line was used to investigate the post-translational maturation of gamma-glutamyltransferase (GGT) and the effects of acute ethanol administration on the expression and glycosylation of this membrane-bound glycoprotein. We found that the two subunits of H5-6 GGT with molecular masses of 55 and 33 kDa were derived from a single glycosylated precursor of 80 kDa. In addition, signals of high molecular mass (more than 90 kDa) were detected. In vitro deglycosylation experiments indicated that N-linked sugars represented about 25% of the molecular weight of the H5-6 enzyme. By use of serial lectin affinity technique, we showed that N-linked sugar chains were mainly of the biantennary complex and hybrid-type, without fucose linkage to the innermost N-acetyl-glucosamine. Ethanol treatment did not seem to affect the expression of GGT and the sialic acid content of the enzyme, but altered its oligosaccharide chain composition both quantitatively and qualitatively.
Odoul
M
M
Centre du Médicament, URA CNRS 597, Université de Nancy I, France.
Bagrel
D
D
Peyrieras
N
N
Bodaud
H
H
Siest
G
G
D000818:Animals; D000431:Ethanol / Q000494:pharmacology*; D006031:Glycosylation / Q000187:drug effects; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008114:Liver Neoplasms, Experimental / Q000201:enzymology*; D008566:Membranes / Q000201:enzymology; D008715:Methionine / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D051381:Rats; D013462:Sulfur Radioisotopes; D014407:Tumor Cells, Cultured / Q000187:drug effects; D005723:gamma-Glutamyltransferase / Q000378:metabolism*
D007527:Isoenzymes; D013462:Sulfur Radioisotopes; D000431:Ethanol; D008715:Methionine; D005723:gamma-Glutamyltransferase