The coordinate release of cytochrome c during apoptosis is rapid, complete and kinetically invariant

Nat Cell Biol. 2000 Mar;2(3):156-62. doi: 10.1038/35004029.


Release of cytochrome c from mitochondria triggers activation of caspase proteases and death of a cell by apoptosis. However, the mechanism and kinetics of cytochrome c release remain unknown. Here we study this event by using green fluorescent protein (GFP)-tagged cytochrome c, and find that the release of cytochrome-c-GFP always precedes exposure of phosphatidylserine and the loss of plasma-membrane integrity - characteristics of apoptotic cells. Once initiated, the release of cytochrome- c-GFP continues until all of the protein is released from all mitochondria in individual cells, within about 5 minutes, regardless of the type or strength of stimulus or the time elapsed since the stimulus was applied. Temperatures ranging from 24 degrees C to 37 degrees C do not change the duration of release, and nor does the addition of caspase inhibitors. Further, we find that the electron-transport chain can maintain the mitochondrial transmembrane potential even after cytochrome c has been released.

Publication types

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

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amino Acid Chloromethyl Ketones / pharmacology
  • Apoptosis*
  • Caspase Inhibitors
  • Caspases / metabolism
  • Cysteine Proteinase Inhibitors / pharmacology
  • Cytochrome c Group / genetics
  • Cytochrome c Group / metabolism*
  • Digitonin / pharmacology
  • Electron Transport / drug effects
  • Electron Transport / radiation effects
  • Enzyme Activation / drug effects
  • Enzyme Activation / radiation effects
  • Enzyme Inhibitors / pharmacology
  • Green Fluorescent Proteins
  • HeLa Cells
  • Humans
  • Image Processing, Computer-Assisted
  • Intracellular Membranes / drug effects
  • Intracellular Membranes / radiation effects
  • Luminescent Proteins / genetics
  • Membrane Potentials / drug effects
  • Mitochondria / metabolism
  • Oligomycins / pharmacology
  • Phosphatidylserines / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sodium Azide / pharmacology
  • Temperature
  • Ultraviolet Rays


  • Amino Acid Chloromethyl Ketones
  • Caspase Inhibitors
  • Cysteine Proteinase Inhibitors
  • Cytochrome c Group
  • Enzyme Inhibitors
  • Luminescent Proteins
  • Oligomycins
  • Phosphatidylserines
  • Recombinant Fusion Proteins
  • benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
  • Green Fluorescent Proteins
  • Adenosine Triphosphate
  • Sodium Azide
  • Caspases
  • Digitonin