Multi-faceted regulation of gamma-glutamylcysteine synthetase

Glutathione is an important antioxidant that is involved in numerous cellul ar activities. gamma-Glutamylcysteine synthetase (gamma GCS) dis a key regu latory enzyme in the synthesis of glutathione. It is a heterodimeric zinc m etalloprotein that belongs to a unique class of proteins that gain activity due to formation of a reversible disulfide bond. The two subunits of gamma GCS exhibit differential and coordinate transcription regulation. In addit ion, the subunits are regulated at the posttranscriptional and posttranslat ional levels. These various levels of regulation allow numerous stimuli to induce or inhibit activity. (C) 2000 Wiley-Liss, Inc.