Influence of @entity535 supply on ribosomes and protein synthesis of perfused XXXX liver.

@entity1522 @entity368 @entity535 @entity2734 @entity1853 @entity2340 @entity6778 @entity376 @entity4857 @entity35 @entity1521 @entity815 @entity369 @entity1889
1. The livers of @entity35 were perfused in situ with medium containing mixtures of @entity1522 in multiples of their concentration in normal @entity35 plasma. The incorporation of labelled @entity535 into protein of the liver and of the perfusing medium increased with increasing @entity535 concentration. During 60min. perfusions, labelling of liver protein reached a plateau, and labelling of medium protein was inhibited when the initial concentration of the @entity535 mixture was more than ten times the normal plasma value. 2. Examination of polysome profiles derived from livers perfused without @entity1522 in the medium showed that the number of large aggregates was decreased and the number of small aggregates, particularly monomers and dimers, was increased with time of perfusion. The addition of @entity1522 to the perfusion medium reversed this polysome shift to an extent that was dependent on the initial concentration of @entity1522 . Polysome profiles derived from livers perfused for 60min. with ten times the normal plasma concentration of @entity1522 were essentially the same as the polysome profiles of normal non-perfused livers. 3. The ability of ribosome preparations from perfused livers to incorporate @entity1522 into protein in vitro decreased with increasing time of perfusion when no @entity1522 were added to the medium, but increased as the concentration of @entity1522 in the perfusion medium was increased. 4. The ability of cell sap from perfused livers to support protein synthesis in vitro was not influenced by the @entity535 concentration of the perfusion medium. 5. Livers were perfused for 60min. with medium containing @entity535 mixtures at ten times the normal plasma concentration but deficient in one @entity535 . Maximal incorporation of labelled @entity535 into liver protein, the stability of the polysome profile and the ability of ribosome preparations to incorporate @entity1522 into protein were found to depend on the presence of 11 @entity1522 : @entity369 , @entity2734 , @entity6778 , @entity368 , @entity376 , @entity1853 , @entity815 , @entity1521 , @entity1889 , @entity2340 and @entity4857 . A mixture of these 11 @entity1522 , at ten times their normal plasma concentration, stimulated the incorporation of labelled @entity535 into liver protein, stabilized the polysome profile and increased the ability of ribosome preparations to incorporate @entity1522 into protein to the same extent as the complete mixture. 6. It is concluded that the availability of certain @entity1522 plays an important role in the control of protein synthesis, possibly by stimulating the ability of ribosomes to become, and to remain, attached to messenger RNA.
