Nitrogen catabolite repression transcriptional regulator; inhibits GLN3 transcription in rich nitrogen; sequesters Gln3p and Gat1p in the cytoplasm; contains glutathione peroxidase activity and can mutate to acquire GST activity; involved in resistance to heavy metal ions and oxidants; catabolite repression, induced by limiting nitrogen, does not occur if Ure2p has polymerized to form the [URE3] prion; translated by cap-dependent and -independent mechanisms; contains homology to human GST