18.104.22.168, GPX4 (PHGPx), 22.214.171.124, 126.96.36.199, L-Cysteinyl-glycine, 188.8.131.52, GSTT1 Homodimer, GSTM1 Homodimer, RX, 184.108.40.206, 220.127.116.11, 18.104.22.168 (22.214.171.124), GPX6, GSTK1 Homodimer, (L)-Cysteine, 126.96.36.199, Glutathione, MGST2 Homotrimer, GSTM2 Homodimer, 188.8.131.52, GSTA1 Homodimer or heterodimer of GSTA1 and GSTA2, MGST Homotrimer, OPLA Homodimer, GSTA4 Homodimer, GPX2 Homotetramer, Glycine, Gamma-(L)-glutamyl-(L)-cysteine, GSTT2 Homodimer, GPX5, GSHB, GSTM4 Homodimer, GSTO1 Homodimer, (L)-Glutamic acid, GSTM5 Homodimer, Glutathione disulfide, L-Amino acid, R-S-Glutathione, 184.108.40.206, GGT1, GSTA5 Homodimer, CD13, GGTL3, GSTA2 Homodimer or heterodimer of GSTA1 and GSTA2, R-S-Alanine, GSTO2, GPX3 Homotetramer, 220.127.116.11, GSTP1 Homodimer, GCL reg, GCL cat, GCTG, GPX7, Gamma-(L)- glutamyl-aminoacid, MGST3, GPX1 Homotetramer, GSHR, 18.104.22.168, 22.214.171.124, R-S-Alanylglycine, 126.96.36.199, 5-Oxo-(L)-proline, GSTM3 Homodimer, GSTA3 Homodimer, MAAI Homodimer
Glutathione can be found in the cell in oxidized ( Glutathione disulfide ) and reduced ( Glutathione ) form. Reduced glutathione can be either directly formed from Glutathione disulfide as the result of activity of Glutathione reductase ( GSHR ) , , or from conjugation of L-Cysteinyl-glycine with (L)-Glutamic acid catalyzed by Gamma-glutamyltranspeptidase 1 precursor ( GGT1 ) or by Gamma-glutamyltransferase light chain 2 ( GGTL3 ) .
L-Cysteinyl-glycine is formed as a result of glutathione conjugation to the L-Amino acid moiety catalyzed by GGT1 and GGTL3 . This reaction results in formation of Gamma-(L)-glutamyl-aminoacid which is converted by Gamma-glutamylcyclotransferase ( GCTG ) , ,  to the 5-Oxo-(L)-proline and L-Amino acid. 5-Oxo-(L)-proline is then reduced to (L)-Glutamic acid by 5-Oxoprolinase ( OPLA ) , , , (L)-Glutamic acid also produced in the Glutathione degradation during the R-S-Alanylglycine formation step.
5-Oxo-(L)-proline and (L)-Cysteine are produced as the result of Gamma-(L)-glutamyl-(L)-cysteine cleavage catalyzed by GCTG . Gamma-(L)-glutamyl-(L)-cysteine itself is synthesized by Glutamate-cysteine ligase catalytic subunit ( GCL cat ) from (L)-Glutamic acid and from (L)-Cysteine , . Glutathione synthetase ( GSHB ) catalyzes subsequent conjugation of Gamma-(L)-glutamyl-(L)-cysteine and Glycine to form Glutathione , . Glycine is supplied from L-Cysteinyl-glycine degradation to Glycine and to (L)-Cysteine, as well as from the R-S-Alanylglycine degradation step.
Glutathione (reduced) reacts with various substrates ( RX ). Those reactions are carried out by a set of enzymes: Glutathione S-transferase A1 ( GSTA1 ), Glutathione S-transferase A2 ( GSTA2 ), Glutathione S-transferase A3 ( GSTA3 ), Glutathione S-transferase A4 ( GSTA4 ), Glutathione S-transferase A5 ( GSTA5 ) , , , , , , Glutathione S-transferase M1 ( GSTM1 ), Glutathione S-transferase M2 ( GSTM2 ) , , Glutathione S-transferase M3 ( GSTM3 ), Glutathione S-transferase M4 ( GSTM4 ), glutathione S-transferase M5 ( GSTM5 ) , , , , , , Glutathione transferase zeta 1 (maleylacetoacetate isomerase) ( MAAI ) , , Glutathione transferase omega-1 ( GSTO1 ), Glutathione transferase omega-2 ( GSTO2 ) , , Glutathione S-transferase theta-1 ( GSTT1 ), Glutathione S-transferase theta-2 ( GSTT2 ) , , Glutathione S-transferase kappa 1 ( GSTK1 ) , , Glutathione S-transferase pi 1 ( GSTP1 ) , , Microsomal glutathione S-transferase 1 ( MGST ), Microsomal glutathione S-transferase 2 ( MGST2 ), and Microsomal glutathione S-transferase 3 ( MGST3 ) , . These reactions produce R-S-Glutathione (glutathione conjugated to a moiety) products. Subsequently R-S-Glutathione lose their (L)-Glutamic acid moieties in reactions catalyzed by GGT1 and GGTL3  to produce R-S-Alanylglycine that is further degraded to R-S-Alanine by Aminopeptidase N ( CD13 ).
Glutathione disulfide can be formed directly from Glutathione in the reaction catalyzed by Glutathione peroxidase 4 ( GPX4 (PHGPx) ) , Glutathione peroxidase 1 ( GPX1 ) , , Glutathione peroxidase 2 ( GPX2 ) , , Glutathione peroxidase 3 (plasma) ( GPX3 ) , , Glutathione peroxidase 6 ( GPX6 ) , , Glutathione peroxidase 7 ( GPX7 ), Glutathione peroxidase 5 ( GPX5 )  and GSHR.
Glutathione disulfide can also be formed through ascorbate metabolism.