This enzyme is located in the mitochondria of all aerobic cells. It is involved in the electron transport system that
functions in oxidative phosphorylation. It accepts electrons from cytochrome b and transfers them to cytochrome
oxidase. In the process the iron of the heme group (which is identical to that of hemoglobin and myoglobin) shifts from
the ferrous to the ferric state. Human cytochrome c has 104 amino acid residues and a molecular weight
of 11,458. In addition to its role in oxidative phosphorylation, release of cytochrome c from the mitochondrial intermembrane
space results in nuclear apoptosis.
This gene encodes cytochrome c, a component of the electron transport chain in mitochondria. The heme group of cytochrome c accepts electrons from the b-c1 complex and transfers electrons to the cytochrome oxidase complex. Cytochrome c is also involved in initiation of apoptosis. Upon release of cytochrome c to the cytoplasm, the protein binds apoptotic protease activating factor which activates the apoptotic initiator procaspase 9. Many cytochrome c pseudogenes exist, scattered throughout the human genome.
Cell death/survival, Apoptosis, Energy pathways
Expression regulated by
Primordial Germ Cell, Oocyte, Cumulus, Granulosa, Theca, Luteal cells, Small luteal cells, Large luteal cells, Stromal cells, Surface epithelium
D'Herde K, et al 2000 reported that ultrastructural localization of cytochrome c in apoptosis
demonstrates mitochondrial heterogeneity.
Release of apoptogenic factors into the cytosol including cytochrome c is
triggering the execution phase of apoptosis through activation of cytoplasmic
effector caspases. How loss of function of the electron transport chain can be
reconciled with an adequate energy supply necessary for executing the apoptotic
program was studied in granulosa cell (GC) sheets cultured up to 72 h without
gonadotrophic support. Cytochrome c was localized ultrastructurally by oxidation
of diaminobenzidine tetrahydrochloride both in living and fixed cells. In
uncultured GC sheets all cells show staining over their entire mitochondrial
population. In 72 h cultured sheets in the absence of FSH pre-apoptotic GC's
display two subsets of mitochondria: normal sized stained mitochondria and small
orthodox mitochondria without demonstrable cytochrome function. Apoptotic cells
contain several mitochondria with preservation of respiratory function besides
unstained orthodox mitochondria. The cytochrome c containing mitochondria
typically display dilated intracristal spaces, a mitochondrial conformation related
to increased ATP production. Cytochrome c release was confirmed by Western
blotting. In 72 h cultures supplemented with FSH, GC's displayed staining over
their entire mitochondrial population. In cultures lacking FSH, but partially
protected from apoptosis through caspase inhibition, the cytochrome c release was
Krysko DV, et al 2001 reported that mitochondrial transmembrane potential changes support the
concept of mitochondrial heterogeneity during apoptosis.
Primordial, Primary, Secondary, Antral, Preovulatory, Corpus luteum