Figure 1.
Complex I in the mitochondrial electron transport chain (mETC). Electrons (e−) are donated to complex I (green) by NADH and to complex II (gray) by FADH2. Both complexes I and II then donate electrons (dashed line) to co-enzyme Q (CoQ) which transfers them complex III (turquoise) and then, via cytochrome C, to complex IV (red). Complexes I, III, and IV of the mETC pump protons to serve as a proton-motive force to drive production of ATP by complex V (blue). Embedded in the inner mitochondrial membrane, complex I is a large (~46 subunits) structure that transfers electrons from NADH to ubiquinone (CoQ). In the mETC, complex I is uniquely inhibited by VAs (red line) and contains NDUFS2, NDUFS4, NDUFS8, and ND2, all proteins discussed in this review.