Acts as the sensor component of the nlrp1 inflammasome, which mediates inflammasome activation in response to various pathogen-associated signals, leading to subsequent pyroptosis (PubMed:30150286). Inflammasomes are supramolecular complexes that assemble in the cytosol in response to pathogens and other damage-associated signals and play critical roles in innate immunity and inflammation (PubMed:30150286). Acts as a recognition receptor (PRR): recognizes specific pathogens and other damage-associated signals, and mediates the formation of the inflammasome polymeric complex (By similarity). In response to pathogen-associated signals, the N-terminal part of nlrp1 is degraded by the proteasome, releasing the cleaved C-terminal part of the protein (NACHT, LRR and PYD domains-containing protein 1, C-terminus), which polymerizes to initiate the formation of the inflammasome complex: the inflammasome recruits and activate pro-inflammatory caspases (caspa and/or caspb), leading to pyroptosis (By similarity). Constitutes the precursor of the nlrp1 inflammasome, which mediates autoproteolytic processing within the FIIND domain to generate the N-terminal and C-terminal parts, which are associated non-covalently in absence of pathogens and other damage-associated signals. Regulatory part that prevents formation of the nlrp1 inflammasome: in absence of pathogens and other damage-associated signals, interacts with the C-terminal part of nlrp1 (NACHT, LRR and PYD domains-containing protein 1, C-terminus), preventing activation of the nlrp1 inflammasome (By similarity). In response to pathogen-associated signals, this part is ubiquitinated and degraded by the proteasome, releasing the cleaved C-terminal part of the protein, which polymerizes and forms the nlrp1 inflammasome (By similarity). Constitutes the active part of the nlrp1 inflammasome (By similarity). In absence of pathogens and other damage-associated signals, interacts with the N-terminal part of nlrp1 (NACHT, LRR and PYD domains-containing protein 1, N-terminus), preventing activation of the nlrp1 inflammasome (By similarity). In response to pathogen-associated signals, the N-terminal part of nlrp1 is degraded by the proteasome, releasing this form, which polymerizes to form the nlrp1 inflammasome complex: the nlrp1 inflammasome complex then directly recruits and activates pro-inflammatory caspases (caspa and/or caspb) activation, leading to subsequent pyroptosis (By similarity). nlrp1 inflammasome is activated by pathogens and other damage-associated signals: activation promotes ubiquitination and degradation of the N-terminal part, releasing the cleaved C-terminal part of the protein (NACHT, LRR and PYD domains-containing protein 1, C-terminus), which polymerizes and forms the nlrp1 inflammasome. Interacts with the C-terminal part of nlrp1 (NACHT, LRR and PYD domains-containing protein 1, C-terminus) in absence of pathogens and other damage-associated signals. Interacts with the N-terminal part of nlrp1 (NACHT, LRR and PYD domains-containing protein 1, N-terminus) in absence of pathogens and other damage-associated signals (By similarity). Homomultimer; forms the nlrp1 inflammasome polymeric complex, a filament composed of homopolymers of this form in response to pathogens and other damage-associated signals (By similarity). The nlrp1 inflammasome polymeric complex associates with pycard/asc (PubMed:30150286). Interacts (via CARD domain) with pycard/asc (via CARD domain); leading to pro-inflammatory caspases (caspa and/or caspb) recruitment (PubMed:30150286). Pro-caspase-a and pro-caspase-b filament formation increases local enzyme concentration, resulting in trans-autocleavage and activation. Active caspa and caspb then processes il1b and il18 precursors, leading to the release of mature cytokines in the extracellular milieu and inflammatory response (By similarity). Co-localizes with pycard, caspa and caspb in the cytoplasm. Expressed in adult spleen, head kidney, gill and skin and also in the embryo. In the embryo, highest expression at 2 hours post-fertilization (hpf) with levels decreasing in later stages. Up-regulated in response to infection with the bacteriim E.tarda. The CARD domain is involved in the interaction with pycard. The C-terminal part of nlrp1 oligomerizes to form the core of the nlrp1 inflammasome filament: in the filament, the CARD domains form a central helical filaments that are promoted by oligomerized, but flexibly linked, UPA regions surrounding the filaments. Autocatalytically cleaved. Autocatalytic cleavage in FIIND region occurs constitutively, prior to activation signals, and is required for inflammasome activity (IL1B release), possibly by facilitating pro-inflammatory caspases (caspa and/or caspb) binding. Both N- and C-terminal parts remain associated non-covalently. Ubiquitinated in response to pathogen-associated signals, leading to its degradation by the proteasome and subsequent release of the cleaved C-terminal part of the protein (NACHT, LRR and PYD domains-containing protein 1, C-terminus), which polymerizes and forms the nlrp1 inflammasome. Morpholino knockdown in embryos 6 hours post-fertilization (hpf) results in reduced caspa and caspb activation following bacterial infection with E.tarda. Belongs to the NLRP family.