Inner mitochondrial membrane proton gradient (PMF) (PMF)

The inner mitochondrial membrane proton gradient, also known as the proton-motive force (PMF), is an electrochemical gradient established by the electron transport chain during cellular respiration [1]. It consists of two components: the electrical potential (mitochondrial membrane potential, Δψm) and the chemical potential (pH gradient, ΔpH) [2]. This gradient is the fundamental energy source used by ATP synthase to drive the phosphorylation of ADP into ATP [1]. Beyond energy transduction, the gradient is essential for the transport of metabolites and proteins into the mitochondria and serves as a key regulator of reactive oxygen species (ROS) production [3]. Pharmacological modulation of this gradient, primarily through mitochondrial uncouplers, is being investigated for the treatment of metabolic disorders such as obesity and nonalcoholic steatohepatitis (NASH) by increasing energy expenditure [4]. These uncouplers act as protonophores that shuttle protons across the membrane, bypassing ATP synthase and dissipating the gradient as heat [2]. However, because the dissipation of this gradient releases energy as heat, therapeutic use is limited by the risk of severe hyperthermia and a narrow therapeutic index [5]. Modern research focuses on developing tissue-specific or self-limiting uncouplers to improve the safety profile of targeting this bioenergetic parameter [4].

Other names

Proton-motive forceMitochondrial electrochemical gradientΔpMitochondrial membrane potential and pH gradientMitochondrial proton gradient

Mitochondrial uncouplers act as protonophores that facilitate the translocation of protons across the inner mitochondrial membrane, bypassing ATP synthase and dissipating the electrochemical gradient as heat [2, 3].