The mitochondrial respiratory chain

This figure shows the subunits of the respiratory chain encoded by nuclear DNA (nDNA) in orange and the subunits encoded by mitochondrial DNA (mtDNA) in yellow. As electrons (e-) flow along the electron-transport chain, protons (H+) are pumped from the matrix to the intermembrane space through complexes I, III, and IV and then back into the matrix through complex V, to produce ATP. Coenzyme Q (CoQ) and cytochrome c (Cyt c) are electron-transfer carriers.