Glutathione transferases: new functions
Well known as detoxification enzymes, the glutathione transferases also function in prostaglandin and steroid hormone synthesis. New uses for the canonical glutathione transferase fold are becoming apparent; the bacterial stringent starvation protein SspA and the yeast prion protein Ure2p (both transcription factors) were found to adopt this fold, but their roles remain unclear. The intracellular chloride ion channel CLIC1 adopts the canonical glutathione transferase fold in its soluble form and appears to undergo radical structural modification as part of its membrane insertion process. The structures of rat and human mitochondrial glutathione transferases have been solved: they adopt a topology similar to that of bacterial disulfide bond isomerases, leading to the suggestion that they have evolved independently of the canonical enzymes. Recent structural studies of integral membrane glutathione S-transferases from microsomes have revealed common patterns of tertiary and quaternary structure.