The Inhibition of Sugar Transport in Chick Embryo Fibroblasts by Cytochalasin B

Abstract

Abstract The mold metabolites, cytochalasin A and B, have been shown to be potent inhibitors of 2-deoxy-d-glucose uptake in cultured cells (Kletzien, R. F., Perdue, J. F., and Springer, A. (1972) J. Biol. Chem. 247, 2964–2966). Cytochalasin B also inhibits the uptake of d-galactose and d-glucosamine in chick embryo fibroblasts at concentrations similar to those used to inhibit the uptake of 2-deoxy-d-glucose. A concentration of cytochalasin B which inhibited 50% of sugar uptake did not affect the ability of the cells to concentrate 2-deoxy-d-glucose as the phosphorylated sugar nor did the drug inhibit the phosphorylation of 2-deoxy-d-glucose by cellular homogenates. Therefore, the inhibition of sugar uptake by cytochalasin B was due to an inhibition of transport across the plasma membrane. This inhibition was analyzed by three methods and was of the linear competitive type with an apparent dissociation constant (Ki) for the inhibitor-carrier complex of 1.45 x 10-7 m.