Mitochondrial oxidative phosphorylation machinery (OXPHOS machinery)

The **mitochondrial oxidative phosphorylation machinery** (OXPHOS machinery) consists of a series of multi-subunit protein complexes—Complex I (NADH-ubiquinone oxidoreductase), Complex II (succinate-ubiquinone oxidoreductase), Complex III (ubiquinone-cytochrome c oxidoreductase), Complex IV (cytochrome c oxidase), and ATP synthase—embedded in the mitochondrial inner membrane[1][4][2][3]. These complexes operate in concert to transfer electrons from metabolic substrates (NADH, FADH2) through the electron transport chain, pumping protons across the inner membrane to generate a proton motive force. This gradient is then used by ATP synthase to convert ADP and inorganic phosphate into ATP, the main cellular energy currency[2][1][4]. Dysfunction or genetic alterations in OXPHOS components lead to a broad spectrum of diseases, including inherited mitochondrial disorders, neurodegeneration, certain cancers, and heart diseases[1][3]. Exposure to environmental toxins, certain drugs, or mutations can inhibit or disrupt the function of these complexes, causing impaired energy production and elevated oxidative stress. OXPHOS machinery is considered a core therapeutic target for modulating bioenergetics in cancer, metabolic disorders, and aging-related conditions, but targeting this system also carries significant safety risks due to its fundamental role in cellular metabolism[1][3][4]. **Note:** - This target is often considered *too broad* for therapeutic purposes, as it represents a collection of complexes and enzymes rather than a single protein. Individual complexes (e.g., Complex I, ATP synthase) are usually targeted specifically, not the whole machinery at once[2][4]. - "Mitochondrial oxidative phosphorylation machinery" is not a standardized name for a single molecular entity, but refers to a collective system, which compromises specificity for drug targeting and biomarker selection[1][3].

Other names

oxidative phosphorylation systemmitochondrial respiratory chainelectron transport chain (when referencing the subcomponents)OXPHOS system

Inhibition of electron transport chain complexes (I–IV); Inhibition of ATP synthase; Uncoupling oxidative phosphorylation (proton gradient dissipation); Modulation of ROS production