title: The "B space" of mitochondrial phosphorylation.
abstract: It was recently shown that, in progressively depolarizing mitochondria, the F(0) -F(1) ATP synthase and the adenine nucleotide translocase (ANT) may change directionality independently from each other (Chinopoulos et al. [2010] FASEB J. 24:2405). When the membrane potentials at which these two molecular entities reverse directionality, termed reversal potential (Erev), are plotted as a function of matrix ATP/ADP ratio, an area of the plot is bracketed by the Erev_ATPase and the Erev_ANT, which we call "B space". Both reversal potentials are dynamic, in that they depend on the fluctuating values of the participating reactants; however, Erev_ATPase is almost always more negative than Erev_ANT. Here we review the conditions that define the boundaries of the "B space". Emphasis is placed on the role of matrix substrate-level phosphorylation, because during metabolic compromise this mechanism could maintain mitochondrial membrane potential and prevent the influx of cytosolic ATP destined for hydrolysis by the reversed F(0) -F(1) ATP synthase.
authors.affiliation: Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary. chinopoulos.christos@eok.sote.hu
authors.forename: Christos
authors.initials: C
authors.lastname: Chinopoulos
mesh_terms: D000818:Animals; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000502:physiology*; D008928:Mitochondria / Q000378:metabolism*; D000226:Mitochondrial ADP, ATP Translocases / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D006180:Proton-Translocating ATPases / Q000378:metabolism
chemical_list: D000226:Mitochondrial ADP, ATP Translocases; D006180:Proton-Translocating ATPases