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. 2023 Jul 6;12(7):1391. doi: 10.3390/antiox12071391

Figure 1.

Figure 1

Coenzyme Q functions. (a) Mitochondrial CoQ shuttles electrons in the electron transport chain and is reduced by dehydrogenases in diverse metabolic pathways. CI, Complex I; CII, Complex II; CIII, Complex III; CIV, Complex IV; CV, Complex V; DHODH, dihydroorotate dehydrogenase; GPDH, glyceraldehyde-3-phosphate dehydrogenase; SQR, sulfide:quinone oxidoreductase; CHDH, choline dehydrogenase; PRDH, proline dehydrogenase; ETF, electron transfer flavoprotein; ETFDH, electron transfer flavoprotein dehydrogenase. (b) CoQH2 is present in cellular membranes and lipoproteins and acts as a chain-terminating antioxidant to inhibit both the initiation and propagation steps of lipid autoxidation. CoQH2 or ascorbate regenerate vitamin E from the tocopheroxyl radical. (c) CoQ functions in the plasma membrane redox system (PMRS) with other antioxidants, such as vitamin E and ascorbate. CoQ is reduced by NAD(P)H:quinone oxidoreductase 1 (NQO1), or NADH-cytochrome b5 reductase (cyb5Red). (d) The CoQ reductase ferroptosis suppressor protein 1 (FSP1) regenerates CoQH2 at the plasma membrane to terminate lipid peroxidation and suppress ferroptosis. Created with Biorender.com (accessed on 23 May 2023).