Glutathione (gamma-L-glutamyl-L-cysteinylglycine) is an important antioxidant molecule, helping to protect the cell against oxidative stress. Expression of the Saccharomyces cerevisiae GSH1 gene, coding for the first enzyme involved in glutathione biosynthesis, is regulated at the level of transcription by oxidants and heavy metals. We have characterised the sequences of the GSH1 promoter responsible for the amino acid-dependent H(2)O(2) regulation of transcription. We show that there are at least two H(2)O(2)-responsive elements in the promoter, neither of which map to the putative Yap1 binding site. Our results suggest that the Yap1 protein plays an important, but indirect role in the H(2)O(2)-dependent regulation of GSH1 transcription.