To examine the effects of the presence of Ehrlich ascites tumours on both the catalytic unit and the substrate/product translocase components of the glucose-6-phosphatase system in vivo, we isolated microsomes from the livers of control and tumour-bearing mice. Samples were analysed immunochemically for the quantity of catalytic unit, stabilizing protein and translocases T2 and T3 proteins. In comparison experiments, a variety of kinetic studies were performed. The most striking findings in tumour-bearing mice were: a 2.5-fold increase in the quantity of translocase T2 protein; increases in the Km and Vmax. for glucose 6-phosphate phosphohydrolase; and a decrease in the Km value for carbamoyl phosphate (carbamoyl-P) of carbamoyl-P:glucose phosphotransferase, all with intact microsomes. The percentage latency at Vmax. decreased for PPi phosphohydrolase and for glucose 6-phosphate phosphohydrolase, but was unaffected for carbamoyl-P:glucose phosphotransferase. These observations support a tumour-related increase in translocase T2 capacity in vivo, as it transports Pi from the microsomal lumen to the medium and carbamoyl-P or PPi from the medium to the microsomal lumen.
Research Article|March 15 1993
The hepatic glucose-6-phosphatase system in Ehrlich-ascites-tumour-bearing mice
R W Lucius;
I D Waddell;
Biochem J (1993) 290 (3): 907-911.
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R W Lucius, I D Waddell, A Burchell, R C Nordlie; The hepatic glucose-6-phosphatase system in Ehrlich-ascites-tumour-bearing mice. Biochem J 15 March 1993; 290 (3): 907–911. doi: https://doi.org/10.1042/bj2900907
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