Also known as gamma-glutamylcysteine synthetase and gamma-ECS (EC:6.3.2.2). This enzyme catalyses the first and rate limiting step in de novo glutathione biosynthesis. Members of this family are found in archaea, bacteria and plants. May and Leaver [1] discuss the possible evolutionary origins of glutamate-cysteine ligase enzymes in different organisms and suggest that it evolved independently in different eukaryotes, from an ancestral bacterial enzyme. They also state that Arabidopsis thaliana gamma-glutamylcysteine synthetase is structurally unrelated to mammalian, yeast and Escherichia coli homologues. In plants, there are separate cytosolic and chloroplast forms of the enzyme.

1: Arabidopsis thaliana gamma-glutamylcysteine synthetase is structurally unrelated to mammalian, yeast, and Escherichia coli homologs. May MJ, Leaver CJ; Proc Natl Acad Sci U S A 1994;91:10059-10063. PMID:7937837