Calcium-binding properties of the mitochondrial channel-forming hydrophobic component

O. Gateau-Roesch, E. Pavlov, A. V. Lazareva, E. A. Limarenko, C. Levrat, N. E.L. Saris, P. Louisot, G. D. Mironova

Research output: Contribution to journalArticlepeer-review


A hydrophobic, low-molecular weight component extracted from mitochondria forms a Ca2+-activated ion channel in black-lipid membranes (Mironova et al., 1997). At pH 8.3-8.5, the component has a high-affinity binding site for Ca2+ with a K(d) of 8 X 10-6 M, while at pH 7.5 this K(d) was decreased to 9 X 10-5 M. B(max) for the Ca2+-binding site did not change significantly with pH. In the range studied, 0.2 ± 0.06 mmol Ca2+/g component were bound or one calcium ion to eight molecules of the component. The Ca2+ binding was strongly decreased by 50-100 mM Na+, but not by K+. Treatment of mitochondria with CaCl2 prior to ethanolic extraction resulted in a high level of Ca2+-binding capacity of the partially purified component. Cyclosporin A, a specific inhibitor of the mitochondrial permeability transition, when added to the mitochondrial suspension, decreased the Ca2+-binding activity of the purified extract severalfold. The calcium-binding capability of the partially purified component correlates with its calcium-channel activity. This indicates that the channel-forming component might be involved in the permeability transition that stimulates its formation.

Original languageEnglish (US)
Pages (from-to)105-110
Number of pages6
JournalJournal of Bioenergetics and Biomembranes
Issue number1
StatePublished - 2000


  • Black-lipid membranes
  • Calcium-binding
  • Cation channel
  • Mitochondria
  • Mitochondrial permeability transition

ASJC Scopus subject areas

  • Physiology
  • Cell Biology


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