AGE-DEPENDENT CHANGES IN RAT-LIVER PRENYLTRANSFERASES

Mevalonate pathway lipids including cholesterol, ubiquinone and dolich ol, are of great importance for cellular function. Many of the enzymes of this pathway are thus strictly regulated. During development of th e rat, the cellular levels of certain of these lipids vary. Prenyltran sferases have been investigated and it is reported here that farnesyl pyrophosphate synthase activity in rat liver cytosol decreases after b irth to a lower, steady level. This decrease is not paralleled by the level of synthase protein, which shows two maxima, one immediately aft er birth and the other 30 days later. cis-Prenyltransferase activity i s low after birth, increases continuously up to day-54 and then decrea ses to a low level which was maintained throughout the remainder of th e study (365 days). Squalene synthase exhibits high activity after bir th, but decreases during the first 100 days thereafter, and subsequent ly remains at the low level thus reached. In contrast to these changes in the activities of the prenyltransferases, the level of cholesterol is constant and the dolichol concentration increases continuously thr oughout the entire period studied.