Arabidopsis thaliana mutant impaired in the production of the gamma-glutamyl peptidases GGP1 and GGP3 has altered glucosinolate levels and accumulates up to 10 related GSH conjugates. The double mutant is impaired in the production of camalexin and accumulates high amounts of the camalexin intermediate GS-IAN upon induction. In addition, the cellular and subcellular localization of GGP1 and GGP3 matches that of known glucosinolate and camalexin enzymes. GSH is the sulfur donor in the biosynthesis of glucosinolates and establish an in vivo function for the only known cytosolic plant gamma-glutamyl peptidases, namely, the processing of GSH conjugates in the glucosinolate and camalexin pathways (Geu-Flores et al. 2011)