Final answer:
Executioner caspases are distinguished from other caspase types by their activation by initiator caspases, substrate specificity, and role in dismantling the cell during apoptosis. They are part of the mitochondrial pathway of apoptosis, where cytochrome C exits the mitochondria and assists in converting procaspases to active caspases.
Step-by-step explanation:
Executioner caspases are a group of enzymes that play a pivotal role in the process of apoptosis, which is the programmed cell death crucial for the removal of abnormal or damaged cells. A key feature of executioner caspases is that they become activated through cleavage by initiator caspases, unlike other caspase types.
Once active, executioner caspases cleave a variety of cellular substrates leading to the dismantling of the cell and its eventual death. These caspases differ from other types due to their substrate specificities and their role in the execution phase of apoptosis, rather than in the initiation of the apoptotic signaling cascade.
The mitochondrial pathway is one method by which executioner caspases are activated. Cytochrome C, a peripheral membrane protein, can exit the mitochondria and trigger the formation of a complex with adaptor proteins in the cytosol.
This complex facilitates the activation of procaspases into active caspases. The cytochrome C-adaptor complex has a high affinity for procaspase, and upon binding, an allosteric change occurs, leading to the release of an active caspase.
In summary, the distinct characteristics of executioner caspases are their activation method via cleavage by initiator caspases, their specific substrate range, and their central role in carrying out the cell death process during apoptosis.