We have investigated the increased rate of glycolysis following transformation of chick embryo fibroblasts by Rous sarcoma virus. In both normal and transformed cells the regeneration of adenosine 5′-diphosphate and orthophosphate was found to be the rate-limiting factor for glycolysis. The plasma membrane Na+-K+-adenosine-5′-triphosphatase (ATPase) was a major contributor to adenosine 5′-diphosphate and orthophosphate regeneration in the fibroblasts, but its contribution was not changed by viral transformation. Neither protein synthesis, nor nucleic acid synthesis, nor microtubular function contributed significantly to the adenosine 5′-diphosphate and orthophosphate pools required for glycolysis either before or after transformation. Measurements of oxidative phosphorylation and of ATPase activity of isolated mitochondria did not reveal any changes following transformation that could account for the increased rate of glycolysis. We propose that an ATPase, which is not sensitive to conventional inhibitors of the Na+-K+-ATPase or mitochondrial ATPase, appears or is increased after transformation.

Culturing chick embryo fibroblasts in the presence of artificial ATPase activators, such as dinitrophenol or gramicidin, mimicked some of the characteristic changes induced by viral transformation. The apparent Km of glycolysis for glucose was decreased by about 10-fold, and the apparent Vmax of hexose transport was increased by about 4-fold. In contrast to transformation, ATPase activators did not change the apparent Vmax of glycolysis or the activity of hexokinase, nor did they mimic the morphological and growth characteristics of transformed cells.

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This investigation was supported by Grant CA-08964, awarded by the National Cancer Institute, Department of Health, Education, and Welfare, and Grant BC-156 from the American Cancer Society. Parts of the data were taken from a Ph.D. dissertation submitted to the Section of Biochemistry, Molecular and Cell Biology of Cornell University (6).

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