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Updated: May 26, 2026

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c
Published on: June 29, 2011
Specific nitration of tyrosines 46 and 48 makes cytochrome c assemble a non-functional apoptosome
José M García-Heredia1, Irene Díaz-Moreno, Antonio Díaz-Quintana
1Instituto de Bioquímica Vegetal y Fotosíntesis, cicCartuja, Universidad de Sevilla-CSIC, Avda. Americo Vespucio 49, Sevilla 41092, Spain.
Abstract:
Under nitroxidative stress, a minor fraction of cytochrome c can be modified by tyrosine nitration. Here we analyze the specific effect of nitration of tyrosines 46 and 48 on the dual role of cytochrome c in cell survival and cell death. Our findings reveal that nitration of these two solvent-exposed residues has a negligible effect on the rate of electron transfer from cytochrome c to cytochrome c oxidase, but impairs the ability of the heme protein to activate caspase-9 by assembling a non-functional apoptosome. It seems that cytochrome c nitration under cellular stress counteracts apoptosis in light of the small amount of modified protein. We conclude that other changes such as increased peroxidase activity prevail and allow the execution of apoptosis.
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