Abstract
B4-2-1 is a Chinese hamster ovary cell mutant previously isolated and characterized as deficient in mannose 6-phosphate receptor activity. B4-2-1 is a pleiotropic mutant, defective in biosynthesis of asparagine-linked oligosaccharides. B4-2-1 is unable to synthesize mannosylphosphoryldolichol; the consequences of this defect on glycosylation are biosynthesis of 1 major lipid-linked oligosaccharide, characterized by its resistance to endoglycosidase H and decreased size; this oligosaccharide is similar to a minor species of lipid-linked oligosaccharide found in parental cells; transfer of this oligosaccharide to newly synthesized proteins; and absence of normal high-mannose oligosaccharides on mature glycoproteins isolated from B4-2-1; glycoproteins from the mutant contain complex oligosaccharides as well as endoglycosidase H-resistant, .alpha.-mannosidase-sensitive species. While the glycosylation defect may alter adversely the function of several glycoproteins in the mutant, including that of the mannose 6-phosphate receptor, it appears to have no effect on the formation or function of the mannose 6-phosphate recognition marker on acid hydrolases of B4-2-1.

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