Figure 1.

Schematic representation of TRAIL receptors and the components of TRAIL-DISC (death-inducing signaling complex). Trimerization of TRAIL receptors (TRAIL-R1/DR4 and TRAIL-R2/DR5) initiates recruitment of adaptor protein FADD. It appears that a GTP-binding adaptor protein DAP3 couples TRAIL receptors to FADD. FADD contains a death effector domain (DD) that promotes recruitment of procaspase-8 to the DISC, by homotypic interactions between the DD present on FADD and procaspase-8. The induced proximity of procaspase-8 molecules is postulated to cause their activation by autocatalytic processes. RIP may also bind to these DR4 and DR5, initiating a cascade causing cell necrosis. Decoy receptors DcR1 and DcR2 lack death domains and do not induce apoptosis.