Caspase-3, also known as apopain, SCA-1, Yama and CPP32, is an aspartatespecific
cysteine protease that belongs to the ICE subfamily of caspases.
Caspase-3 is expressed in cells as an inactive precursor from which the p17
and p11 subunits of the mature caspase-3 are proteolytically generated during
apoptosis. The caspase-3 precursor is first cleaved at Asp 175-Ser 176 to
produce the p11 subunit and the p20 peptide. Subsequently, the p20 peptide
is cleaved at Asp 28-Ser 29 to generate the mature p17 subunit. The active
caspase-3 enzyme is a heterodimer composed of two p17 and two p11 subunits.
At the onset of apoptosis, caspase-3 proteolytically cleaves PARP at a
Asp 216-Gly 217 bond. During the execution of the apoptotic cascade, activated
caspase-3 releases SREBP from the membrane of the ER in a proteolytic
reaction that is distinct from their normal sterol-dependent activation.
Caspase-3 cleaves and activates SREBPs between the basic helix-loop-helix
leucine zipper domain and the membrane attachment domain.