Protoplasts of Saccharomyces strain 1016 took up [3H]glucosamine in the presence of an energy source; mannose was chosen to minimize randomization. It accumulated in the soluble intracellular pool primarily as UDP-N-acetyl[3H]glucosamine along with a small amount of [3H]glucosamine 6-phosphate. The antibiotic tunicamycin (TM) at 10 μg/ml did not affect the levels of these metabolites or inhibit the formation of the Nacetylglucosamine polymer, chitin, but did prevent the incorporation of [3H]glucosamine into mannan peptides and the synthesis of invertase. In vitro incorporation of [14C]mannose from GDP-[14C]mannose into mannan in a membrane preparation was not sensitive to 100 μg of TM/ml. TM appears to inhibit an N-acetylglucosaminyl transferase essential for glycoprotein biosynthesis. Binding of [3H]TM reflects its association with the plasma membrane fraction. This material could be recovered in an unaltered form by extraction with chloroform/methanol. If 0.2% phosphatidyl choline or phosphatidyl serine was added simultaneously with the [3H]TM, the binding of [3H]TM was greatly reduced, and the inhibitory effects of TM on protoplasts were prevented; however, addition of phospholipid 20 min later did not eliminate the inhibition, although about 80% of the bound [3H]TM was removed. TM interacts with lipophilic membrane components as well as inhibiting glycoprotein synthesis. © 1976.
Kuo, S. C., & Lampen, J. O. (1976). Tunicamycin inhibition of [3H]glucosamine incorporation into yeast glycoproteins: Binding of tunicamycin and interaction with phospholipids. Archives of Biochemistry and Biophysics, 172(2), 574–581. https://doi.org/10.1016/0003-9861(76)90110-7