Inflammasome sensor, which mediates inflammasome activation in response to various pathogen-associated signals, leading to subsequent pyroptosis of CD4(+) T-cells and macrophages. 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. Acts as a recognition receptor (PRR): recognizes specific pathogens and other damage-associated signals, such as HIV-1 protease activity or Val-boroPro inhibitor, and mediates CARD8 inflammasome activation. In response to pathogen-associated signals, the N-terminal part of CARD8 is degraded by the proteasome, releasing the cleaved C-terminal part of the protein (Caspase recruitment domain-containing protein 8, C-terminus), which polymerizes to initiate the formation of the inflammasome complex: the CARD8 inflammasome directly recruits pro-caspase-1 (proCASP1) independently of PYCARD/ASC and promotes caspase-1 (CASP1) activation, which subsequently cleaves and activates inflammatory cytokines IL1B and IL18 and gasdermin-D (GSDMD), leading to pyroptosis. Ability to sense HIV-1 protease activity leads to the clearance of latent HIV-1 in patient CD4(+) T-cells after viral reactivation; in contrast, HIV-1 can evade CARD8-sensing when its protease remains inactive in infected cells prior to viral budding. Also acts as a negative regulator of the NLRP3 inflammasome. May also act as an inhibitor of NF-kappa-B activation.; Constitutes the precusor of the CARD8 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 CARD8 inflammasome: in absence of pathogens and other damage-associated signals, interacts with the C-terminal part of CARD8 (Caspase recruitment domain-containing protein 8, C-terminus), preventing activation of the CARD8 inflammasome. In response to pathogen-associated signals, this part is ubiquitinated by the N-end rule pathway and degraded by the proteasome, releasing the cleaved C-terminal part of the protein, which polymerizes and forms the CARD8 inflammasome (Probable).; Constitutes the active part of the CARD8 inflammasome. In absence of pathogens and other damage-associated signals, interacts with the N-terminal part of CARD8 (Caspase recruitment domain-containing protein 8, N-terminus), preventing activation of the CARD8 inflammasome. In response to pathogen-associated signals, the N-terminal part of CARD8 is degraded by the proteasome, releasing this form, which polymerizes to form the CARD8 inflammasome complex: the CARD8 inflammasome complex then directly recruits pro-caspase-1 (proCASP1) and promotes caspase-1 (CASP1) activation, leading to gasdermin-D (GSDMD) cleavage and subsequent pyroptosis.
