Mitochondrial electron transport chain and oxidative phosphorylation machinery (ETC/OXPHOS)

The mitochondrial electron transport chain (ETC) and oxidative phosphorylation (OXPHOS) machinery are a series of multi-subunit protein complexes (Complexes I-V) and electron carriers located within the inner mitochondrial membrane [1]. This system's primary biological role is the production of adenosine triphosphate (ATP) through the coupling of electron transfer from NADH and FADH2 to oxygen with the pumping of protons to create an electrochemical gradient [1, 5]. Beyond energy metabolism, the ETC is a major site of reactive oxygen species (ROS) generation and serves as a critical regulator of cellular redox states and apoptosis [2]. Dysfunction in these components is a hallmark of primary mitochondrial diseases, such as Leigh syndrome, and contributes significantly to the progression of neurodegenerative diseases like Parkinson's and Alzheimer's [2, 4]. In oncology, the OXPHOS machinery is targeted to exploit the metabolic vulnerabilities of cancer cells, particularly those resistant to conventional therapies [4]. Drugs like metformin and the clinical candidate IACS-010759 act by inhibiting Complex I, thereby disrupting the energy supply and biosynthetic pathways of sensitive cells [3, 4]. However, targeting this machinery presents significant challenges, including the risk of systemic toxicity and lactic acidosis due to the essential role of mitochondria in high-energy organs [2, 3].

Other names

Respiratory chainMitochondrial respiratory chainOXPHOS systemMitochondrial oxidative phosphorylation system

Inhibition of electron transfer within Complexes I-IV, inhibition of ATP synthase (Complex V), or uncoupling of the electrochemical gradient to disrupt ATP production and alter cellular metabolism [1, 3, 4].