Figure 2.

Simplified representation of the mitochondrial respiratory chain and targets of selected mitotropic substances. The inner mitochondrial membrane and the compartments of the respiratory chain are shown. Complexes I–IV generate a proton gradient (↑∆µH⁺) so that ATP can be synthesized via complex V (ATP synthase) (↓∆µH⁺). Electrons move from complex I via complex II and ubiquinol to complex III. Cytochrome c transports the electrons from complex III to complex IV. UCP (uncoupling protein) allows protons to pass through the mitochondrial membrane without chemiosmotic coupling, thus uncoupling the respiratory chain from ATP generation and serving, among other things, thermogenesis.