Studies on transcription of the yeast URA2 gene.

The multifunctional protein carbamoylphosphate synthetase (CPSase)-aspartate transcarbamylase (ATCase) encoded by the URA2 gene catalyses the first two steps of the yeast pyrimidine pathway. An excess of the final product, the intracellular UTP (uridine triphosphate), inhibits both the transcription of the URA2 gene and the enzymatic activities. Results presented in this paper suggest that transcription of URA2 is negatively regulated (repression-derepression) and establish that this regulation is less efficient in the flow of the pyrimidine pathway than feedback inhibition.