An Impaired Uptake of Glucosamine in Tunicamycin Resistant Chinese Hamster Ovary Cells

Tunicamycin resistant mutants (TM^R) were isolated and characterized from Chinese hamster ovary cells. One feature of this TM^R mutants was a marked decrease in incorporation of radioactive glucosamine, both into membrane glycoproteins and G protein of vesicular stomatitis virus.

The cellular uptake and incorporation into acid insoluble materials of various radioactive substances, including glucosamine, galactosamine, mannose, 2-deoxyglucose and leucine, was examined for the purpose of determination whether the reduced incorporation of radioactive glucosamine into glycoproteins was due to a defect in the glycosylation step or decreased uptake of glucosamine by cells.

While incorporation of glucosamine and 2-deoxyglucose into acid insoluble fractions was reduced strikingly in the mutants, the incorporation of mannose and leucine were the same as in the parent cells.

The uptake of glucosamine in TM^R cells was lower than that in the wild type cells, and the Km value for glucosamine uptake differed between the mutants and wild type cells. There was no obvious difference in the uptake of 2-deoxyglucose and mannose.