Isozymes
Several isozymes are encoded by different genes, which vary in celullar location and substrate specificity. Glutathione peroxidase 1 (GPx1) is the most abundant version, found in the cytoplasm of nearly all mammalian tissues, whose preferred substrate is hydrogen peroxide. Glutathione peroxidase 4 (GPx4) has a high preference for lipid hydroperoxides; it is expressed in nearly every mammalian cell, though at much lower levels. Glutathione peroxidase 2 is an intestinal and extracellular enzyme, while glutathione peroxidase 3 is extracellular, especially abundant in plasma. So far, eight different isoforms of glutathione peroxidase (GPx1-8) have been identified in humans.
| Gene | Locus | Enzyme |
|---|---|---|
| GPX1 | Chr. 3 p21.3 | glutathione peroxidase 1 |
| GPX2 | Chr. 14 q24.1 | glutathione peroxidase 2 (gastrointestinal) |
| GPX3 | Chr. 5 q23 | glutathione peroxidase 3 (plasma) |
| GPX4 | Chr. 19 p13.3 | glutathione peroxidase 4 (phospholipid hydroperoxidase) |
| GPX5 | Chr. 6 p21.32 | glutathione peroxidase 5 (epididymal androgen-related protein) |
| GPX6 | Chr. 6 p21 | glutathione peroxidase 6 (olfactory) |
| GPX7 | Chr. 1 p32 | glutathione peroxidase 7 |
| GPX8 | Chr. 5 q11.2 | glutathione peroxidase 8 (putative) |
Read more about this topic: Glutathione Peroxidase