ABSTRACT
In higher organisms, apoptosis induction originates through ligand engagement and receptor activation outside the cell or from stress-induced signals within the cell. Both of these pathways, termed the extrinsic and intrinsic pathways, respectively, converge on common cell death effector machinery comprised of a series of cysteine proteases called caspases. Caspases are the key effector components of apoptosis and cleave their substrates after aspartate residues. Once activated, they cleave substrate proteins within the cell, leading to the morphological changes associated with apoptosis. Adaptor proteins act as scaffolds that organize signaling complexes and also recruit pro-and anti-apoptotic regulatory proteins that provide critical control points and influence caspase activation. These core components are represented in both the extrinsic and intrinsic pathway machinery and
Introduction ............................................................................................................ 253 Extrinsic Pathway ..................................................................................................254
