APOPTOTIC ACTIVITY OF REAPER IS DISTINCT FROM SIGNALING BY THE TUMOR-NECROSIS-FACTOR RECEPTOR-1 DEATH DOMAIN

REAPER (RPR) is a 65-amino acid protein that is critical activator of programmed cell death in Drosophila. On the basis of sequence alignmen t data, it was recently proposed that RPR might represent an ancestral molecule from which the death domain in a number of proteins may have evolved, We tested this idea by examining the activity of mutations i n RPR that parallel inactivation mutations of the tumor necrosis facto r receptor 1 death domain. The RPR mutants retained potent apoptotic f unction, suggesting that cell death activity mediated by RPR is distin ct from signaling by the tumor necrosis factor receptor 1 death domain .