Studies on the control of pyrimidine biosynthesis in human diploid cell strains. II. Effects of 5-azaorotic acid, barbituric acid, and pyrimidine precursors on cellular phenotype.

Abstract

Human diploid cell strains grown in the presence of 6-azauridine, and certain other inhibitors of pyrimidine synthesis, develop augmented levels of activity for the final 2 sequentially acting enzymes in the bio-synthetic pathway leading to uridine-5[image]-monophosphate. Evidence suggests that the increase in activity is more likely to be due to the accumulation within the cell of a precursor of uridine-5[image]-mono-phosphate than to depletion of the cellular pool of this nucleotide. The data also suggest that the active precursor may be dihydroorotic acid.