The effect of various metabolites on incorporation in vitro of labelled amino acids into protein of normal rat diaphragm

Abstract

Incorporation into rat-diaphragm protein in vitro of C14 from a medium containing (C14) alanine is greater when (C14)-glucose or -pyruvate is present in the medium than in their absence. Addition of insulin further increases incorporation of C14 in both the presence and the absence of (C14)-glucose or -pyruvate. Addition of oxoglutarate to the medium substantially depresses incorporation into protein of C14 from (C14) glutamic acid, and slightly depresses that from alanine, glycine and leucine. Incorporation of C14 from aspartic acid is somewhat enhanced under these conditions. Incorporation into diaphragm protein of C14 from a medium containing (C14) glutamic acid is vastly increased when (C14) oxoglutarate is also added. Addition of oxaloacetate severely depresses incorporation into protein of C14 from (C14)-alanine and -glutamic acid, and slightly from glycine and leucine. Incorporation of C14 from aspartic acid is not affected. In the presence of NaHCl4O3, C14 is incorporated into protein of normal rat diaphragm. Incorporation into protein of normal rat diaphragm of C14 from (C14) alanine is depressed in the presence of carbutamide or tolbutamide whether or not glucose or pyruvate is present. The results are largely, but not entirely, explicable on the assumption that transamination reactions, together with carboxylation, can proceed in isolated rat diaphragm under the conditions of our experiments.