Component of the IMD signaling pathway and is required for the host defense against Gram-negative bacteria. Interacts with Dredd, promotes cleavage of Dredd and is necessary and sufficient for enhancing Dredd-induced apoptosis. Interacts (via N-terminus) with Dredd; likely to bind Dredd simultaneously with Diap2 to form a trimeric complex (PubMed:10934188, PubMed:22549468). Interacts with imd (PubMed:12433364). Expressed between 3-12 hours of embryonic development.