We have used a Chinese hamster ovary cell line deficient in N-acetylglucosaminyltransferase 1 activity (Lecl) to study the effects of altered asparaginelinked oligosaccharides on the structure, biosynthesis, and function of glucose transporter protein. lmmunoblots of membranes of Lecl cells show a glucose transporter protein of M, 40,000, whereas membranes of wild-type (WT) cells contain a broadly migrating t M, 55,000 form similar to that observed in several other mammalian tissues. The total content of immunoreactive glucose transporters in Lecl cells is 3.5-fold greater than that of WT cells. Digestion with endoglycosidases, treatment with inhibitors of glycosylation, and interactions with agarose-bound lectins demonstrate that glucose transporters of both cell lines derive from a similar M, 38,000 core polypeptide and that both contain asparagine-linked oligosaccharide. Transporters in Lecl cells contain primarily "undecorated" but "trimmed" mannose-type asparagine-linked oligosaccharides, while the protein in WT cells contains a mixture of "decorated" and "trimmed" asparagine-linked oligosaccharides. Biosynthetic and turnover studies demonstrate that Lecl cells, in contrast to WT cells, are unable fully to process the core asparagine-linked oligosaccharides of maturing glucose transporters. When radiolabeled in methionine-deficient medium both Lecl and WT cells show similar rates of synthesis and turnover of glucose transporter proteins. It should be noted, however, that starvation for a critical amino acid may alter the ability ofthe cell to synthesize or degrade proteins. The abilities of Lecl and WT cells to transport hexoses and to interact with the inhibitor cytochalasin B are very similar. The results indicate that, although altered asparagine-linked glycosylation can affect the content and biogenesis of glucose transporters, these changes do not greatly modify cellular hexose uptake. The possibility that alterations in asparagine-linked glycosylation may change the cell surface localization or acquisition of a "functional conformation" of the glucose transporter is also suggested.