The "B space" of mitochondrial phosphorylation

J Neurosci Res. 2011 Dec;89(12):1897-904. doi: 10.1002/jnr.22659. Epub 2011 May 3.

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.

Publication types

  • Review

MeSH terms

  • Animals
  • Humans
  • Membrane Potential, Mitochondrial / physiology*
  • Mitochondria / metabolism*
  • Mitochondrial ADP, ATP Translocases / metabolism
  • Phosphorylation / physiology
  • Proton-Translocating ATPases / metabolism

Substances

  • Mitochondrial ADP, ATP Translocases
  • Proton-Translocating ATPases