DEATH DOMAIN RECEPTORS AND THEIR ROLE IN CELL DEMISE

Apoptotic signals ape transduced by five death domain-containing recep tors-TNFR1, Fas, DR3, DR4, and DR5-by binding to their ligands, The in tracellular portion of all these receptors contains a region, approxim ately 80 amino acids long, referred to as the ''death domain'' (DD), O n activation by its ligand, the DD recruits various proteins that medi ate cell death. These proteins, in turn, recruit other proteins via th eir DDs or death effector domains (DED), The actual destruction of the cell, however, is accomplished by serial activation of a family of pr oteases referred to as caspases, Cell death is, in part, regulated by transmembrane decoy receptors that contain either none of or only part of the DD, This article briefly reviews what is known about the recep tors and other proteins involved in apoptosis, In addition, because nu merous proteins that mediate apoptosis have been discovered independen tly and simultaneously and thus are known by many different names, a c omprehensive cross-referenced list of these proteins is provided.