COMPARTMENTATION AND CONTROL OF ARGININE METABOLISM IN NEUROSPORA

The fate of [14C]arginine derived from the medium or from biosynthesis was examined in Neurospora growing in arginine-supplemented medium. In both cases, the label entered the cytosol, where it was used efficiently for both protein synthesis and catabolism before mixing with the majority of the endogenous [12C]arginine pool. Both metabolic processes used the same cytosolic arginine pool. The nonorganellar cytoplasm contained approximately 20% of the intracellular arginine pool when the cells were growing in arginine-supplemented medium. Compartmentation of arginine was probably a significant factor in controlling arginine metabolism in Neurospora. The significance of these results for studies of amino acid metabolism in other eukaryotic systems was discussed.