A decrease in the number of active mouse liver ribosomes during aging

Abstract

Microsomes, deoxycholate treated polysomes, and molar KCl treated monosomes were prepared from eleven and twenty-eight month old mouse liver. The number of active ribosomes were estimated in these preparations by measuring the ability to form peptidylpuromycin under conditions in which no recycling of ribosomes occur. The results showed that the decreased synthetic capacity of preparations from the older animals [as measured by endogenous and polyphenylalanine synthesis in response to poly(U)] was most likely a result of a smaller proportion of active ribosomes rather than a reduced efficiency of individual ribosomes.