Cell death via apoptosis is a fundamental cellular function triggered by the cell death receptor family and their ligands which signal through downstream adaptor molecules and the caspase protease family. All caspases exist in a precursor form composed of a prodomain, and large and small catalytic subunits. Caspases require a cleavage adjacent to an aspartate to liberate one large and one small subunit, which can then associate into an a2b2 tetramer.
