Figure 1. Signaling mechanism parallels between eukaryotic Death-superfamily domains and prokaryotic effector-associated domains (EADs) in their biological contexts.

(A) Extrinsic and (B) intrinsic pathways in eukaryotic apoptosis signaling. (C) Schematic representation of the interactions mediated by Death domains in various metazoan signaling processes. (D) Cartoon structural representation of the Death-Death interaction in the FADD-FAS complex (PDB: 3EQZ) and the Pyrin domain-based protein-templated assembly of filamentous polymeric complexes in NLRP6 (PDB: 6NCV). (E) Representative ternary biological conflict systems where the EADs, predicted to perform roles comparable to eukaryotic Death domains, were discovered. (F) Schematic representation of the interactions mediated by the EADs in prokaryotic biological conflict systems that are predicted to lead to a highly regulated counter-invader response.