Käynnistäjäkaspaseihin

Käynnistäjäkaspaseihin are enzymes belonging to the caspase family, which are a group of proteases playing a crucial role in programmed cell death, or apoptosis. In many organisms, including humans, caspases are synthesized as inactive pro-caspases that are then activated through proteolytic cleavage. Käynnistäjäkaspaseihin, as their name suggests, are the initiator caspases. Their primary function is to initiate the apoptotic cascade by cleaving and activating downstream effector caspases.

These initiator caspases are typically activated by specific upstream signals that trigger apoptosis. For example, in the intrinsic apoptotic pathway, which is initiated by cellular stress or damage, initiator caspases like caspase-8 and caspase-9 are recruited to protein complexes such as the death-inducing signaling complex (DISC) or the apoptosome. Within these complexes, pro-caspases undergo auto-activation or are activated by other caspases, leading to their proteolytic processing and the formation of active enzyme units.

Once activated, käynnistäjäkaspaseihin then cleave and activate effector caspases, such as caspase-3, caspase-6, and caspase-7. These effector caspases are responsible for dismantling the cell by degrading essential cellular proteins and DNA, ultimately leading to the characteristic morphological changes of apoptosis. The precise activation mechanisms and specific roles of different käynnistäjäkaspaseihin can vary between different cell types and signaling pathways. Their dysregulation is implicated in various diseases, including cancer and neurodegenerative disorders.