Fig. 1: Structure and function of complex I.

a Reduction of quinone (Q) triggers proton pumping in the membrane domain of Complex I. The subunit naming is based on Thermus thermophilus Complex I. b Closeup of antiporter-like subunits, Nqo12 (left, lateral helix not shown) and Nqo13 (right). Conserved residues along the hydrophilic axis are shown, and the trans-membrane broken helices TM7a/b and TM12a/b are highlighted in solid colour.