Synthesis and degradation of the major hepatic phosphofructokinase isozyme in rat liver and hepatoma 3924-A

Abstract

Summary The rates of synthesis were determined for the major phosphofructokinase isozyme in rat liver and the fast growing, poorly differentiated hepatoma 3924-A. Its rate of synthesis, which was measured as rate of incorporation of leucine, was approximately 2.3-fold greater in the hepatoma compared to the normal liver. Using the double labeling technique, which has been demonstrated to estimate degradation rate constants, Glass and Doyle, J. Biol. Chem. , 247, 5234 (1972), the 3H/14C ratios for this isozyme in the liver and hepatoma were nearly the same, which implied that the degradative process for this isozyme is similar for both tissues. These results indicate for this isozyme that it has attained a steady state level in the hepatoma 3924-A different from the liver, which is described by a 2–3 fold increase in its rate of synthesis and degradation.