Chopper, a new death domain of the p75 neurotrophin receptor that mediatesrapid neuronal cell death

The cytoplasmic juxtamembrane region of the p75 neurotrophin receptor (p75( NTR)) has been found to be necessary and sufficient to initiate neural cell death. The region was named "Chopper" to distinguish it from CD95-like dea th domains. A 29-amino acid peptide corresponding to the Chopper region ind uced caspase- and calpain-mediated death in a variety of neural and nonneur al cell types and was not inhibited by signaling through Trk (unlike killin g by full-length p75(NTR)). Chopper triggered cell death only when bound to the plasma membrane by a lipid anchor, whereas non-anchored Chopper acted in a dominant-negative manner, blocking p75(NTR)-mediated death both in vit ro and in vivo. Removal of the ectodomain of p75(NTR) increased the potency of Chopper activity, suggesting that it regulates the association of Chopp er with downstream signaling proteins.