Smac/Diablo is a 21 kDa mammalian mitochondrial protein that functions as a regulatory component during apoptosis. Upon mitochondrial stress, Smac/Diablo is released from mitochondria and competes with caspases for binding of IAPs (inhibitor of apoptosis proteins). The interaction of Smac/Diablo with IAPs relieves the inhibitory effect of the IAPs on caspases.
