SOURCE OF ATP FOR HEXOKINASE-CATALYZED GLUCOSE PHOSPHORYLATION IN TUMOR-CELLS - DEPENDENCE ON THE RATE OF OXIDATIVE-PHOSPHORYLATION RELATIVE TO THAT OF EXTRAMITOCHONDRIAL ATP GENERATION

We isolated highly intact and tightly coupled mitochondria from the ra t ascites hepatoma cell line AH130 by disruption of the cell membrane by nitrogen cavitation. These isolated mitochondria were found to have essentially the same functional properties as rat liver mitochondria, but unlike the latter, hexokinase (HK) was bound to their membrane. U sing the tumor mitochondrial preparation, we examined the source of AT P for phosphorylation of glucose by HK under conditions in which intra - and extramitochondrial ATP-generation systems operated separately or together. Results showed that the membrane-bound HK utilized ATP deri ved from the most efficiently operating ATP generation system, i.e., o xidative phosphorylation. However, when the rate of extramitochondrial ATP generation was much greater than that of oxidative phosphorylatio n, HK used ATP from the extramitochondrial ATP-generation system. (C) 1997 Elsevier Science B.V.