Changes in phosphate-activated glutaminase activities determined in in
tact cells and isolated mitochondria have been followed during mouse E
hrlich ascites carcinoma development. Glutaminase activities parallel
the levels of poly(A)(+) RNAs encoding for the mitochondrial phosphate
activated glutaminase. During the exponential growth phase, maximum a
ctivity was observed and the relative abundance of glutaminase mRNA si
gnificantly increased with regard to the stationary growth phase. The
presented results show that tumor phosphate-activated glutaminase is s
ubject to long-term regulation by differential gene expression.