Members of the NTR/TNFR family mediate apoptosis in many tissues, yet sequence homology has not been detected in their intracellular domains except for a ‘death domain’ in TNFR-I and Fas. Here, a region of the 75 kDa neurotrophin receptor (NTR) has been aligned with this apoptosis-inducing motif. Peptides at the carboxyl terminus of each domain potentially form amphiphilic helices, one of which (in NTR) resembles mastoparan, a G-protein activating peptide. Molecular models of three death-region peptides suggest that observed sequence similarities reflect a common structure, perhaps capable of undergoing an induced coil to helix transition.
