Cytochrome c (CYCS) (CYCS)

Cytochrome c is a highly conserved small heme protein (approximately 12 kDa) primarily located in the mitochondrial intermembrane space, where it serves as an essential component of the electron transport chain (UniProt: P99999). It functions as a mobile electron carrier, transferring electrons from cytochrome bc1 complex (Complex III) to cytochrome c oxidase (Complex IV), a process vital for ATP synthesis via oxidative phosphorylation (NCBI Gene: 54205). Beyond its bioenergetic role, cytochrome c is a central trigger for the intrinsic pathway of apoptosis; its translocation from the mitochondria to the cytosol leads to the formation of the apoptosome and the activation of the caspase cascade (PubMed: 8887625). In clinical contexts, mutations in the CYCS gene are associated with thrombocytopenia 4, while its dysregulation is a hallmark of cancer and neurodegeneration (StatPearls: NBK554417). Pharmacological modulation of cytochrome c often involves stabilizing its interaction with cardiolipin to preserve mitochondrial integrity, as seen with the investigational drug elamipretide, or inducing its release to promote cell death in oncology (DrugBank: DB12250). Additionally, the release of cytochrome c into the systemic circulation serves as a clinical biomarker for cellular injury and mitochondrial distress in conditions such as myocardial infarction and liver failure (PubMed: 15155835).

Other names

CYCHCSTHC4Cytochrome c, somatic

Stabilization of mitochondrial membrane association or induction of cytosolic release to trigger the apoptosome.