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Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria
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Multi-parameter Measurement of the Permeability Transition Pore Opening in Isolated Mouse Heart Mitochondria

Published on: September 7, 2012

Control of the mitochondrial permeability transition pore by high-affinity ADP binding at the ADP/ATP translocase in

R A Haworth1, D R Hunter

  • 1Institute for Enzyme Research, Madison, Wisconsin 53706, USA.

Journal of Bioenergetics and Biomembranes
|January 5, 2002
PubMed

Insights

Low ADP binding to the ADP/ATP translocase inhibits mitochondrial permeability transition. This process is conformation-dependent, suggesting the translocase

Area of Science:

  • Mitochondrial physiology
  • Biochemistry
  • Cellular respiration

Background:

  • The mitochondrial inner membrane's permeability transition is crucial for cellular energy production and cell death.
  • The ADP/ATP translocase plays a key role in regulating mitochondrial function and adenine nucleotide transport.

Purpose of the Study:

  • To investigate the effect of ADP binding on the Ca2+-induced mitochondrial permeability transition.
  • To elucidate the role of ADP/ATP translocase conformation in regulating the permeability transition pore (PTP).

Main Methods:

  • Utilizing a shrinkage assay on mitochondria that had already undergone permeability transition.
  • Employing specific inhibitors like carboxyatractyloside (CAT) and bongkrekic acid (BKA) to probe translocase conformation.
  • Measuring the impact of Ca2+ and ADP on mitochondrial membrane permeability and ADP/ATP translocase binding.

Main Results:

  • Low ADP binding to the ADP/ATP translocase inhibited Ca2+-induced mitochondrial permeability transition.
  • Inhibition was prevented by CAT and potentiated by BKA, indicating a role for translocase conformation.
  • Ca2+ addition led to ADP removal and a slow decay of inhibition, suggesting ADP dissociation from the translocator.

Conclusions:

  • The probability of permeability transition pore (PTP) formation is higher when the ADP/ATP translocase is in the CAT conformation compared to the BKA conformation.
  • ADP binding and removal can shift the translocator between BKA and CAT conformations, influencing PTP formation even in deenergized mitochondria.

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