NOD1 is a member of the NOD (nucleotide-binding oligomerization domain) family, a group of proteins that are involved in innate immune defense. NOD1 contains an N-terminal caspase recruitment domain (CARD), a centrally located nucleotide-binding domain (NBD), and ten tandem leucine-rich repeats (LRRs) in its C-terminus. The CARD is involved in apoptotic signaling, and NOD1 activates caspase-9 and NF-κB. LRRs participate in protein-protein interactions, and mutations in the NBD may affect the process of oligomerization and subsequent function of the LRR domain. This protein is an intracellular pattern-recognition receptor (PRR) that initiates inflammation in response to a subset of bacteria through the detection of bacterial diaminopimelic acid.