Fig. 1.

Sites of ROS production. Many different sites of ROS production exist within a cell. Most of them are located in the mitochondrial environment such as the complexes of the respiratory chain: complex I (I), complex II (II), complex III (III), or mitochondrial glycerophosphate dehydrogenase (mGPDH) next to α-ketoglutharate dehydrogenases (α-KGDH), electron transfer flavoprotein (ETF) and ETF ubiquinone oxidoreductase, pyruvate dehydrogenase (PDH), aconitase, alternative oxidase (AO), complex IV (IV), dihydroorotate dehydrogenase (DHODH), external NADH dehydrogenase (NADH DH), protein p66^Shc, cytochrome (cyt) b5 reductase, monoamine oxidase (MAO) and nitric oxide synthase (NOS). Other proteins or organelles can also contribute to ROS production. Respiratory chain complexes are displayed in blue, other ROS contributors in green, organelles in violet. (For interpretation of the references to color in figure legend, the reader is referred to the web version of the article.)