Mitochondrial electron transport chain protein complex (Complex I, Complex III, Complex IV, Complex V) (ETC complexes I, III, IV, V)

Proteins of the mitochondrial electron transport chain complexes I, III, IV, and V are multi-subunit enzyme systems resident in the inner mitochondrial membrane. Collectively, they participate in the transfer of electrons from metabolic substrates to oxygen (via NADH and FADH2), pumping protons to generate an electrochemical gradient subsequently used to produce ATP by Complex V (F1F0 ATP synthase). These complexes are crucial for cellular energy production (oxidative phosphorylation), and defects or pharmacological inhibition lead to impaired ATP synthesis, accumulation of metabolic intermediates, and production of reactive oxygen species. Each complex has a distinct protein composition but their collective function is required for life and cellular viability. Dysfunction is implicated in primary mitochondrial diseases, metabolic syndromes, neurodegeneration, and aging.

Other names

Electron transport chain (ETC) proteinsOxidative phosphorylation complexesRespiratory chain complexes I, III, IV, and VNADH:ubiquinone oxidoreductase (Complex I)Cytochrome bc1 complex (Complex III)Cytochrome c oxidase (Complex IV)ATP synthase (Complex V)

Enzyme inhibition (blocking electron/proton transfer in specific complexes) Disruption of proton gradient Inhibition of ATP synthesis Modulation of ROS generation