May be involved in inflammation and recognition of cytosolic pathogen-associated molecular patterns (PAMPs) not intercepted by membrane-bound receptors. Acts as a negative regulator of the type I interferon signaling pathway by serving as an adapter to promote DTX4-mediated ubiquitination of activated TBK1, and its subsequent degradation. Suppresses NF-kappaB induction by the cytokines TNFA and IL1B, suggesting that it operates at a point of convergence in these two cytokine signaling pathways. Interacts with CHUK/IKKA, inhibiting its kinase activity. Experimental confirmation may be lacking for some isoforms. The pyrin domain is sufficient for suppression of NF-kappaB activity, it adopts a typical death domain fold, but in contrast to several NLRP family pyrin domains it doesn't bind homotypically to the ASC adapter, which supports the observation that NLRP4 has no effect on IL1B activation. Belongs to the NLRP family. Truncated C-terminus.