title: Protein synthesis by liver ribosomes from aged rats.
abstract: The age-related decrease in protein synthesis by cell-free systems has been traced to a factor which can be obtained by high salt extraction of young polysomes. Such extracts, when added to old ribosomes in young post-ribosomal supernate, stimulate the level of Poly(U)-directed protein synthesis. Extracts of old polysomes have essentially no effect. The deficient factor is not EF-2 and is highly unlikely to be EF-1, as this component resides almost entirely in the post-ribosomal supernates used in the reaction mixture. Since initiation factors are not necessary for Poly(U)-directed protein synthesis and EF-1 and EF-2 do not appear to be involved, the nature of the soluble factor which is deficient in old ribosomes appears to lie outside of proteins which are commonly implicated in the age-related slowing of protein synthesis.
mesh_terms: D000375:Aging; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002474:Cell-Free System / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors / Q000378:metabolism; D014176:Protein Biosynthesis; D051381:Rats; D011916:Rats, Inbred F344; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D000596:Amino Acids; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors