Thiol protease that acts as a mediator of programmed cell death (PubMed:29898893, PubMed:28314590). Initiates pyroptosis, a programmed lytic cell death pathway through cleavage of Gasdermin-D (GSDMD): cleavage releases the N-terminal gasdermin moiety (Gasdermin-D, N-terminal) that binds to membranes and forms pores, triggering pyroptosis (PubMed:29898893). During non-canonical inflammasome activation, cuts CGAS and may play a role in the regulation of antiviral innate immune activation (PubMed:28314590). Strict requirement for Asp at the P1 position. It has a preferred cleavage sequence of Tyr-Val-Ala-Asp-|- but also cleaves at Asp-Glu-Val-Asp-|-. Heterotetramer that consists of two anti-parallel arranged heterodimers, each one formed by a 20 kDa (p20) and a 10 kDa (p10) subunits (By similarity). Interacts with MEFV (PubMed:17431422). Interacts with SERPINB1; this interaction regulates CASP5 activity (PubMed:30692621). Expressed in barely detectable amounts in most tissues except brain, highest levels being found in lung, liver and skeletal muscle. Up-regulated by bacterial lipopolysaccharides (LPS). The two subunits are derived from the precursor sequence by an autocatalytic mechanism. Most abundant isoform. Most abundant isoform. May be produced at very low levels due to a premature stop codon in the mRNA, leading to nonsense-mediated mRNA decay. Produced by alternative initiation at Met-71 of isoform 1. Belongs to the peptidase C14A family. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.