Hypothesis: the mitochondrial NO(*) signaling pathway, and the transduction of nitrosative to oxidative cell signals: an alternative function for cytochrome C oxidase.
Nitric oxide (NO(*)) signaling is diverse, and involves reaction with free radicals, metalloproteins, and specific protein amino acid residues. Prominent among these interactions are the heme protein soluble guanylate cyclase and cysteine residues within several proteins such as caspases, the executors of apoptosis. Another well characterized site of NO(*) binding is the terminal complex of the mitochondrial respiratory chain, cytochrome c oxidase, although the downstream signaling effects of this interaction remain unclear. Recently, it has been recognized that the intracellular formation of hydrogen peroxide (H(2)O(2)) by controlled mechanisms contributes to what we term "redox tone," and so controls the activity and activation thresholds of redox-sensitive signaling pathways. In this hypothesis paper, it is proposed that NO(*)-dependent modulation of the respiratory chain can control the mitochondrial generation of H(2)O(2) for cell signaling purposes without affecting ATP synthesis.
Brookes
Paul
P
Center for Free Radical Biology and Department of Pathology, Molecular and Cellular Pathology Division, University of Alabama at Birmingham, Birmingham, AL 35294-0019, USA.
Darley-Usmar
Victor M
VM
D000255:Adenosine Triphosphate / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D003576:Electron Transport Complex IV / Q000378:metabolism*; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000378:metabolism; D008564:Membrane Potentials; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D009569:Nitric Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D015398:Signal Transduction
D005609:Free Radicals; D009569:Nitric Oxide; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D003576:Electron Transport Complex IV; D010100:Oxygen