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Function of the mitochondrial outer membrane as a diffusion barrier in health and diseases

F N Gellerich1, S Trumbeckaite, J R Opalka

  • 1Muskellabor der Neurologischen Klinik der Martin-Luther-Universität Halle-Wittenberg, Halle/Saale, Germany.

Biochemical Society Transactions
|May 18, 2000
PubMed

Insights

The mitochondrial outer membrane controls metabolite exchange and ADP compartmentation. A leaky outer membrane can trigger apoptosis and decrease cellular energy production, detectable via specific assays.

Area of Science:

  • Mitochondrial biology
  • Cellular bioenergetics

Background:

  • The mitochondrial outer membrane regulates transport between the cytosol and intermembrane space.
  • This membrane is crucial for metabolite exchange and cellular signaling.
  • Dynamic ADP compartmentation in the intermembrane space is hypothesized.

Purpose of the Study:

  • To review evidence supporting dynamic ADP compartmentation within the mitochondrial intermembrane space.
  • To explore the consequences of mitochondrial outer membrane permeability.
  • To highlight methods for detecting outer membrane leakiness.

Main Methods:

  • Review of experimental evidence.
  • Spectrophotometric and oxygraphic methods for detecting outer membrane leakiness in saponin-skinned fibers.

Main Results:

  • The outer membrane acts as a diffusion barrier, creating concentration gradients for molecules like adenine nucleotides.
  • These gradients are essential for ADP shuttle function via creatine kinases and adenylate kinases.
  • Outer membrane leakiness leads to the release of apoptosis-inducing factors (e.g., cytochrome c) and a decrease in cytosolic phosphorylation potential.

Conclusions:

  • The mitochondrial outer membrane plays a critical role in regulating cellular energy metabolism and apoptosis.
  • Outer membrane integrity is vital for maintaining mitochondrial function.
  • Detecting outer membrane leakiness is important for understanding acute mitochondrial impairment, particularly during ischemia/reperfusion injury.

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