[Age dependent changes of biosynthesis of proteins (author's transl)].

The activity of KC1-washed ribosomes from the liver and the kidney of rats in a poly(U) dependent cell free system with [3H]-phe-tRNA as phenylalanine donor is highly increased by the cytosolic fraction from liver, brain, kidney and testicles. The activity of the cell sap of these tissues decreases significantly with increasing age of the rats from which the cytosolic fractions were prepared. Ribosomes do not undergo age dependent alterations with regard to their activity in poly(U) systems supported by cell sap from rat liver. The results are discussed with regard to age dependent change of the content of cytosolic translation factors.