Mitochondrial oxidative phosphorylation complexes (OXPHOS complexes) (OXPHOS complexes)

Mitochondrial oxidative phosphorylation (OXPHOS) complexes are a series of five multi-subunit enzyme assemblies (Complexes I-V) located in the inner mitochondrial membrane that facilitate cellular respiration and energy production [1.1.1, 1.1.4]. These complexes work in concert to transfer electrons from NADH and FADH2 to molecular oxygen, creating a proton gradient that drives the synthesis of adenosine triphosphate (ATP) by ATP synthase (Complex V) [1.1.1, 1.5.5]. Beyond bioenergetics, the OXPHOS system is a major source of reactive oxygen species (ROS) and plays critical roles in apoptosis, calcium signaling, and metabolic regulation [1.1.2, 1.1.3]. Dysfunction in these complexes is a hallmark of primary mitochondrial diseases and is implicated in the pathogenesis of neurodegenerative disorders, cardiovascular diseases, and aging [1.1.5, 1.2.1]. In oncology, many tumors exhibit a dependency on OXPHOS for survival and metastasis, leading to the development of inhibitors like IACS-010759 and the repurposing of drugs like metformin and atovaquone [1.2.3, 1.3.4]. However, targeting these complexes is challenging due to a narrow therapeutic index and the risk of severe side effects such as lactic acidosis and neurotoxicity [1.4.2, 1.4.3]. Therapeutic strategies often involve partial inhibition to induce a beneficial stress response or complete inhibition to selectively kill metabolic-dependent cancer cells [1.2.1, 1.3.2]. Monitoring efficacy and safety typically involves measuring metabolic biomarkers like lactate and pyruvate levels [1.5.1].

Other names

Mitochondrial respiratory chainElectron transport chain complexesRespiratory complexes I-VOXPHOS systemMitochondrial electron transport assembly

Inhibition of electron transfer through the respiratory chain, disruption of the mitochondrial proton gradient, and suppression of ATP synthesis, often leading to activation of the AMPK pathway and metabolic reprogramming [1.2.1, 1.3.1].