Mitochondrial electron transport chain complex (ETC complex (or mitochondrial ETC))

The mitochondrial electron transport chain complex, often referred to as the mitochondrial electron transport chain (ETC) or mitochondrial respiratory chain, is not a single protein but a series of four large transmembrane protein complexes (complex I-IV) embedded in the inner mitochondrial membrane, together with mobile electron carriers ubiquinone (coenzyme Q) and cytochrome c[1][2][3][4]. Electrons derived from metabolic substrates (primarily via NADH and FADH2) are transferred through these complexes, culminating in the reduction of molecular oxygen to water. This process establishes an electrochemical proton gradient across the inner mitochondrial membrane, which is utilized by ATP synthase (complex V) to generate most of the cell’s ATP through oxidative phosphorylation[1][2][3][4]. Dysfunction of one or more ETC complexes is implicated in a wide range of diseases, including neurodegenerative and cardiovascular conditions, mitochondrial genetic diseases, cancer, and metabolic disorders. The ETC is the primary site of mitochondrial reactive oxygen species (ROS) production, which can contribute to pathology under conditions of oxidative stress[2][5].

Other names

Electron transport chainmitochondrial ETCmitochondrial respiratory chainmitochondrial respiratory complexoxidative phosphorylation complex

Inhibition of electron flow between specific complexes (e.g., complex I inhibition by rotenone), Uncoupling of oxidative phosphorylation, Disruption of proton gradient, Enhancement of electron shuttling