Caspases are a family of cysteine proteases that play a central role in apoptotic cell death. They exist as inactive zymogens and are activated by specific signals, leading to the systematic degradation of cellular proteins. Caspases are essential for apoptosis, as their activation correlates with the onset of cell death, and their inhibition reduces apoptosis. Studies show that caspase-deficient animals exhibit severe developmental defects, highlighting their critical role in programmed cell death. Caspases have a conserved structure, consisting of an N-terminal prodomain, a large subunit with an active site cysteine, and a C-terminal small subunit. Activation occurs through proteolysis of the interdomain linker, which removes the prodomain and allows the enzyme to function as a tetramer. Caspases recognize and cleave substrates with aspartate residues at the P1 position, and their substrate specificity varies among different caspase isoforms. Caspase activation can occur through autoactivation, transactivation, or proteolysis by other proteinases. Adapter molecules, such as FADD and APAF-1, facilitate the oligomerization of caspases, promoting their activation. For example, FADD links death receptors to procaspase-8, while APAF-1 binds to cytochrome c and activates procaspase-9. Once activated, caspases transactivate other procaspases, leading to a cascade amplification of apoptosis. They also cleave various substrates, including pro- and anti-apoptotic proteins, structural proteins, and signaling molecules, which contribute to the characteristic features of apoptosis, such as cell shrinkage, chromatin condensation, and DNA fragmentation. Caspases also play a role in inflammatory processes, with some caspases functioning as cytokine processors. Non-caspase proteinases, such as granzyme B, can also activate caspases and induce apoptosis. The regulation of caspase activity is crucial for maintaining cellular homeostasis. Dysregulation of caspase activity can lead to diseases such as cancer or neurodegenerative disorders. Understanding caspase function and regulation is essential for developing therapeutic strategies for apoptosis-related diseases.Caspases are a family of cysteine proteases that play a central role in apoptotic cell death. They exist as inactive zymogens and are activated by specific signals, leading to the systematic degradation of cellular proteins. Caspases are essential for apoptosis, as their activation correlates with the onset of cell death, and their inhibition reduces apoptosis. Studies show that caspase-deficient animals exhibit severe developmental defects, highlighting their critical role in programmed cell death. Caspases have a conserved structure, consisting of an N-terminal prodomain, a large subunit with an active site cysteine, and a C-terminal small subunit. Activation occurs through proteolysis of the interdomain linker, which removes the prodomain and allows the enzyme to function as a tetramer. Caspases recognize and cleave substrates with aspartate residues at the P1 position, and their substrate specificity varies among different caspase isoforms. Caspase activation can occur through autoactivation, transactivation, or proteolysis by other proteinases. Adapter molecules, such as FADD and APAF-1, facilitate the oligomerization of caspases, promoting their activation. For example, FADD links death receptors to procaspase-8, while APAF-1 binds to cytochrome c and activates procaspase-9. Once activated, caspases transactivate other procaspases, leading to a cascade amplification of apoptosis. They also cleave various substrates, including pro- and anti-apoptotic proteins, structural proteins, and signaling molecules, which contribute to the characteristic features of apoptosis, such as cell shrinkage, chromatin condensation, and DNA fragmentation. Caspases also play a role in inflammatory processes, with some caspases functioning as cytokine processors. Non-caspase proteinases, such as granzyme B, can also activate caspases and induce apoptosis. The regulation of caspase activity is crucial for maintaining cellular homeostasis. Dysregulation of caspase activity can lead to diseases such as cancer or neurodegenerative disorders. Understanding caspase function and regulation is essential for developing therapeutic strategies for apoptosis-related diseases.