The model eukaryote Saccharomyces cerevisiae is well suited to investigate the causes of metabolic disturbance. PRPP [5-phospho-D-ribosyl-1(α)-pyrophosphate] may be regarded as a junction of carbon and nitrogen metabolism. As a result of this central position, perturbations in its synthesis can give rise to many unexpected cellular events, such as impaired cell integrity. We have taken advantage of S. cerevisiae's genetic tractability to investigate the metabolic links responsible for connecting the biochemical intermediate PRPP to apparently unrelated cellular functions. This approach provides insight into the co-ordination of different biological processes.