May play a role in innate immunity by disrupting the interaction between PYCARD and NLRP3, thereby regulating the NLRP3 inflammasome (PubMed:17339483, PubMed:17178784). May also inhibit NF-kappa-B signaling distally by affecting the nuclear accumulation of RELA (PubMed:17339483, PubMed:24871464). Interacts with PYCARD/ASC (via pyrin domain) (PubMed:17339483, PubMed:17178784). Interacts with NLRP2 (via pyrin domain) (PubMed:17178784). Recruited to specks formed by PYCARD within the cytoplasm. Predominantly expressed in peripheral blood. Weakly expressed in testis. Absent from the genome of domestic mammals and New World monkeys it is found in the genome of hominids and Old World monkeys. Likely derived from retrogene insertion of an NLRP2/NLRP7-like gene, it has probably arisen recently in the mammalian genomes where it is under purifying selection.