fig1

Figure 1. Gamma-glutamyl transferase (GGT) and increased cardiometabolic stress. The glutathione breakdown initiated by GGT action and synthesis of G-SH is shown. In the presence of ferrous iron (Fe²⁺), cysteinyl-glycine - a product of GGT action—initiates a series of reactions leading to the generation of reactive oxygen species and increased oxidative stress. The G-SH consumption due to increased oxidative stress or xenobiotics leads to low antioxidant defense, which contributes to increased oxidative and cardiometabolic stress. The scheme supports the view that GGT elevation may be a marker of antioxidant inadequacy. Cys: Cysteine; GGT: gamma-glutamyl transferase; Glu: glutamate; Gly: glycine; ROS: reactive oxygen species. The asterisk next to the cell membrane domain of GGT shows cellular stimuli promoting GGT elevation in the setting of glutathione depletion and low antioxidant defense.