Transport and phosphorylation of hexoses in normal and rous sarcoma virus‐transformed chick embryo fibroblasts

Effects of transformation by Rous sarcoma virus on sugar uptake and activity and the subcellular distribution of hexokinase isozymes in chick embryo fibroblasts were examined. Transformation caused a several‐fold increase in the maximum velocity for uptake of 2‐deoxyglucose without a significant change in K_m. Cytochalasin B (CB), was used to differentiate between the effects of transformation on facilitated diffusion and the nonsaturable (CB‐insensitive) mode. Transformation was found to stimulate 2‐deoxyglucose transport by both mechanisms, but the increase in transport by the CB‐insensitive mode was greater. Transformation enhances the activity of hexokinase, the enhancement being confined to the particulate fraction of the enzyme. Heat‐inactivation and electrophoretic mobility studies showed that although hexokinase Type I is the major form in both normal and transformed fibroblasts, there is a significant increase in the proportion of the Type II isozyme in the transformed cells.