Figure 2.

| Mitochondria functionality. Reduced GSH due to ROS is translocated into the mitochondria, where it acts as a cofactor for GPx for the conversion of hydrogen peroxide into water. Due to reduced levels of GSH, H₂O₂ keeps on accumulating in the mitochondria, which diffuses from the mitochondria and starts causing cellular damage. Adaptor protein p66shc under stress conditions translocates into the mitochondria and starts producing H₂O₂ on its own in the absence of superoxide dismutase, which further leads to higher levels of H₂O₂. Stress conditions generated due to lower mitochondrial glutathione levels cause the oxidation of the cardiolipin–cytochrome c complex. As a result, cytochrome c diffuses through the mitochondria via BAX/BAK created pores and starts the apoptosis via caspase-3. P66shc also reduces the membrane potential to release cyt c into the cytosol. Upper head arrows show increased expression, while lower head arrows represent a decreased expression. Green circles with negative symbol represents membrane negative potential whereas green circles with plus symbol presents reduction in the membrane potential. O₂^•–, superoxide; SOD, superoxide dismutase; H₂O₂, hydrogen peroxide; GPx, glutathione peroxidase; GSH, glutathione; GSSG, glutathione disulfide; CLOOH, oxidized cardiolipin; BAX, B-cell lymphoma-2(Bcl-2)-associated X protein; BAK, Bcl-2 antagonist/killer; cty c, cytochrome c; p66shc, 66 kDa adaptor protein and member of the Src homologous-collagen homologue.