Cytochrome c is released in a single step during apoptosis

Cell Death Differ. 2005 May;12(5):453-62. doi: 10.1038/sj.cdd.4401596.


Release of cytochrome c from mitochondria is a central event in apoptotic signaling. In this study, we utilized a cytochrome c fusion that binds fluorescent biarsenical ligands (cytochrome c-4CYS (cyt. c-4CYS)) as well as cytochrome c-green fluorescent protein (cyt. c-GFP) to measure its release from mitochondria in different cell types during apoptosis. In single cells, the kinetics of cyt. c-4CYS release was indistinguishable from that of cyt. c-GFP in apoptotic cells expressing both molecules. Lowering the temperature by 7 degrees C did not affect this corelease, but further separated cytochrome c release from the subsequent decrease in mitochondrial membrane potential (DeltaPsi(m)). Cyt. c-GFP rescued respiration in cells lacking endogenous cytochrome c, and the duration of cytochrome c release was approximately 5 min in a variety of cell types induced to die by various forms of cellular stress. In addition, we could observe no evidence of caspase-dependent amplification of cytochrome c release or changes in DeltaPsi(m) preceding the release of cyt. c-GFP. We conclude that there is a general mechanism responsible for cytochrome c release that proceeds in a single step that is independent of changes in DeltaPsi(m).

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Apoptosis / radiation effects
  • Biomarkers
  • Cytochromes c / metabolism*
  • Dactinomycin / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Green Fluorescent Proteins / metabolism
  • HeLa Cells
  • Humans
  • Jurkat Cells
  • Kinetics
  • Ligands
  • Membrane Potentials / drug effects
  • Microscopy, Video
  • Mitochondria / drug effects
  • Mitochondria / physiology
  • Protein Synthesis Inhibitors / pharmacology
  • Staurosporine / pharmacology
  • Temperature
  • Tumor Necrosis Factor-alpha / pharmacology
  • Ultraviolet Rays


  • Biomarkers
  • Enzyme Inhibitors
  • Ligands
  • Protein Synthesis Inhibitors
  • Tumor Necrosis Factor-alpha
  • Green Fluorescent Proteins
  • Dactinomycin
  • Cytochromes c
  • Staurosporine