The effect of dietary protein deficiency on albumin synthesis and on the concentration of active albumin messenger ribonucleic acid in rat liver.

In rats fed on a protein-deficient diet, albumin synthesis as a percentage of total liver protein synthesis falls from the normal value of approx. 15% to about 8%. We have extracted total cytoplasmic RNA from individual rat livers and measured the concentration of active albumin mRNA by translation in a reticulocyte lysate system from which the endogenous mRNA had been removed [Pelham & Jackson (1976) Eur. J. Biochem. 67, 247-256]. In this messenger-dependent system it is possible to measure the synthesis of albumin as a proportion of the overall protein synthesis promoted by the addition of the hepatic RNA. The results show that the concentration of translatable albumin mRNA in samples of total cytoplasmic RNA from livers of protein-deficient rats is decreased markedly. These findings suggest that dietary protein supply affects selectively the synthesis and/or functional stability of albumin mRNA in rat liver.