NALP1 (DEFCAP/NAC/CARD7) is an NLR (Nod-like receptor) family member that has been implicated in the regulation of apoptosis and inflammatory responses. Structurally, NALP contains an amino-terminal PYRIN domain, followed by a nucleotide-binding site (NBS), a leucine-rich repeat region (LRR), and a carboxy-terminal CARD domain. NALP1 interacts strongly with caspase-2 and weakly with caspase-9, and induces apoptosis when overexpressed. Similar to a related Ced-4 family member Apaf-1, it was also shown to be involved in cytochrome c-dependent caspase activation. It has also been shown to be part of the "inflammasome" comprised of caspase-1, caspase-5, and Pycard/ASC, which is critical in the processing of pro-inflammatory cytokines like IL-1?. Two major isoforms were identified for NALP1, which differ in a 44 amino acid region within the LRR. In addition, like NALP3, a short NALP1 isoform lacking the LRR (NALP1s) likely exists. Polymorphisms in NALP1 have been associated with autoimmune diseases and susceptibility to toxins.

NALP1 is autoproteolytically processed into a large N-terminal and a small C-terminal fragment, which are non-covalently associated. Upon activation, the C-terminal is released and forms inflammasomes with other proteins.