Identification of a ryanodine receptor in rat heart mitochondria

J Biol Chem. 2001 Jun 15;276(24):21482-8. doi: 10.1074/jbc.M101486200. Epub 2001 Apr 10.


Recent studies have shown that, in a wide variety of cells, mitochondria respond dynamically to physiological changes in cytosolic Ca(2+) concentrations ([Ca(2+)](c)). Mitochondrial Ca(2+) uptake occurs via a ruthenium red-sensitive calcium uniporter and a rapid mode of Ca(2+) uptake. Surprisingly, the molecular identity of these Ca(2+) transport proteins is still unknown. Using electron microscopy and Western blotting, we identified a ryanodine receptor in the inner mitochondrial membrane with a molecular mass of approximately 600 kDa in mitochondria isolated from the rat heart. [(3)H]Ryanodine binds to this mitochondrial ryanodine receptor with high affinity. This binding is modulated by Ca(2+) but not caffeine and is inhibited by Mg(2+) and ruthenium red in the assay medium. In the presence of ryanodine, Ca(2+) uptake into isolated heart mitochondria is suppressed. In addition, ryanodine inhibited mitochondrial swelling induced by Ca(2+) overload. This swelling effect was not observed when Ca(2+) was applied to the cytosolic fraction containing sarcoplasmic reticulum. These results are the first to identify a mitochondrial Ca(2+) transport protein that has characteristics similar to the ryanodine receptor. This mitochondrial ryanodine receptor is likely to play an essential role in the dynamic uptake of Ca(2+) into mitochondria during Ca(2+) oscillations.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Calcium / metabolism*
  • Calcium-Transporting ATPases / antagonists & inhibitors
  • Calcium-Transporting ATPases / metabolism
  • Cytosol / metabolism
  • Intracellular Membranes / physiology
  • Intracellular Membranes / ultrastructure
  • Kinetics
  • Microscopy, Immunoelectron
  • Mitochondria, Heart / drug effects
  • Mitochondria, Heart / physiology*
  • Mitochondria, Heart / ultrastructure
  • Mitochondrial Swelling / drug effects
  • Mitochondrial Swelling / physiology
  • Models, Biological
  • Radioligand Assay
  • Rats
  • Ryanodine / pharmacokinetics
  • Ryanodine / pharmacology
  • Ryanodine Receptor Calcium Release Channel / analysis
  • Ryanodine Receptor Calcium Release Channel / physiology*
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases


  • Ryanodine Receptor Calcium Release Channel
  • Ryanodine
  • Adenosine Triphosphate
  • Sarcoplasmic Reticulum Calcium-Transporting ATPases
  • Calcium-Transporting ATPases
  • Calcium