Reduced synthesis of [14C]mannosyl oligosaccharide-lipid by membranes prepared from concanavalin A-resistant Chinese hamster ovary cells.

We compared the synthesis of mannosyl oligosaccharide-lipid by membranes of wild type and concanavalin A-resistant Chinese hamster ovary cells during incubations with GDP-[14C]mannose and UDP-N-acetylglucosamine. The membranes prepared from exponentially growing mutant cells incorporated 10- to 70-fold less [14C]mannose into oligosaccharide-lipid than did membranes of wild type cells. The lectin-resistant cells are temperature-sensitive for growth. Using temperature-resistant revertants, we showed that the reduction in labeled oligosaccharide-lipid correlated with resistance to concanavalin A rather than with the temperature-sensitive phenotype. Tunicamycin, a specific inhibitor of oligosaccharide-lipid synthesis, reduced the synthesis of the oligosaccharide-lipid by membranes of wild type cells but did not affect the residual synthesis measured in membranes of the mutant cells. As the mutant cells were grown to high density, there was a marked increase in the synthesis of oligosaccharide-lipid by the membranes.