Participates in the detoxification process. ATP + L-cysteine + L-glutamate = ADP + gamma-L-glutamyl-L-cysteine + H(+) + phosphate Sulfur metabolism; glutathione biosynthesis; glutathione from L-cysteine and L-glutamate: step 1/2. Homodimer or monomer when oxidized or reduced, respectively. Up-regulated by cadmium and cu(2+). The Cys-178-Cys-398 disulfide bridge is known to modulate the enzyme activity according to the redox status. The oxidized form constitutes the active enzyme. Belongs to the carboxylate-amine ligase family. Glutamate--cysteine ligase type 2 subfamily.