Final answer:
Release of cytochrome c from the mitochondria triggers apoptosis through activation of caspases, a group of proteolytic enzymes. Cytochrome c forms a complex with Apaf-1 and procaspase-9, initiating a cascade of events leading to cellular breakdown. This process is regulated by Bcl2 family proteins, such as Bak and Bax.
Step-by-step explanation:
The release of cytochrome c from the mitochondria is a key event in the initiation of apoptosis, or programmed cell death. Cytochrome c is a peripheral membrane protein that can dissociate from the mitochondrial cristal membrane and enter the cytosol. Once in the cytosol, cytochrome c binds to adaptor protein Apaf-1, leading to the formation of an aggregate that can attract and bind to procaspase-9. This binding induces a conformational change in the procaspase, activating it to its caspase form. Caspase-9, in turn, is a proteolytic enzyme that activates other caspases, thereby initiating a proteolytic cascade that leads to the auto-digestion of the cell.
Active caspases play a crucial role in degrading cellular components during apoptosis. The release of cytochrome c from mitochondria is regulated by proteins such as Bak and Bax, which are part of the Bcl2 family and form channels in the outer mitochondrial membrane. Their activation allows cytochrome c to exit into the cytosol and trigger the downstream events necessary for cell death.