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. The Cys-186-Cys-406 disulfide bridge is known to modulate the enzyme activity according to the redox status. The oxidized form constitutes the active enzyme (By similarity). Belongs to the carboxylate-amine ligase family. Glutamate--cysteine ligase type 2 subfamily.