Caspase 8

Caspase 8 is a protein that in humans is encoded by the CASP8 gene. It is a member of the caspase family. Sequential activation of caspases plays a central role in the execution-phase of cell apoptosis. Caspases exist as inactive proenzymes that undergo proteolytic processing at conserved aspartic residues to produce two subunits, large and small, that dimerize to form the active enzyme.

Function

Caspase 8 is a key player in the extrinsic apoptosis pathway, a process that allows the cell to respond to external death signals. The protein is synthesized as an inactive precursor that is processed to form an active enzyme when cells receive signals to undergo apoptosis. It is involved in the initiation phase of the extrinsic apoptosis pathway and serves to link the death receptor signaling complex to the execution phase of apoptosis.

Structure

Caspase 8 is a heterotetramer that consists of two large and two small subunits. The large subunit contains a peptidase domain with the active site, and the small subunit is necessary for the formation of the active enzyme.

Clinical significance

Mutations in the CASP8 gene have been associated with a variety of cancers, including head and neck cancer, gastric cancer, and breast cancer. In addition, polymorphisms in this gene are thought to influence susceptibility to autoimmune diseases and viral infections.

See also

• Caspase 3
• Caspase 9
• Apoptosis