A lectin-resistant mouse lymphoma cell line is deficient in glucosidase II, a glycoprotein-processing enzyme.

摘要: Glycosylation of asparagine residues glycoproteins occurs by the transfer a glucose3mannose9N-acetylglucosamine2 (Glc3Man9GlcNAc2) oligosaccharide from lipid carrier to nascent protein. Normally, this is quickly followed stepwise removal glucose which are arranged in sequence: Glc1 leads 2Glc1 3Glc1 3Man. We now report studies demonstrate that lectin-resistant mutant BW5147 mouse lymphoma cell line deficient enzyme removes two inner residues. This (PHAR2.7) was selected for resistance cytotoxic effects Phaseolus vulgaris leukoagglutinating lectin (Trowbridge, I. S., Hyman, R., Ferson, T., and Mazauskas, C. (1978) Eur. J. Immunol. 8, 716-723). Glycopeptides prepared cells equilibrium-labeled with either [2-3H]mannose or [6-3H]galactose were characterized using affinity chromatography, treatment specific endo- exoglycosidases, sizing paper methylation analysis. Approximately 50% radioactivity [3H]mannose-labeled glycopeptides present as glucosylated high mannose-type oligosaccharides whereas parent labeled under similar conditions lack detectable amounts these species. Using [3H]galactose labeling, major identified Glc2Man9GlcNAc2 Glc2Man8GlcNAc2. In vitro assays demonstrated cannot remove 1 3-linked Removal outer normal. conclude data PHAR2.7 glucosidase II, newly glycosylated proteins.