Pattern recognition receptor (PRR) that detects bacterial peptidoglycan fragments and other danger signals and thus participates in both innate and adaptive immune responses (PubMed:19043560, PubMed:22672233, PubMed:27099311). Ligand binding triggers oligomerization that facilitates the binding and subsequent activation of the receptor interacting protein-2/RIPK2. RIPK2 subsequently recruits the kinase TAK1 to activate NF-kappa-B and MAPK signaling pathways (PubMed:10880512). Regulates also antiviral response elicited by dsRNA and the expression of RLR pathway members by targeting IFIH1 and TRAF3 to modulate the formation of IFIH1-MAVS and TRAF3-MAVS complexes leading to increased transcription of type I IFNs (PubMed:32169843). Besides recognizing pathogens, participates in surveillance of cellular homeostasis through sensing and binding to the cytosolic metabolite sphingosine-1-phosphate and then initating inflammation process (PubMed:33942347). In addition, plays a role in insulin trafficking in beta cells in a cell-autonomous manner. Mechanistically, upon recognizing cognate ligands, NOD1 and RIPK2 localize to insulin vesicles where they recruit RAB1A to direct insulin trafficking through the cytoplasm (By similarity). Forms homooligomers(PubMed:10880512). Interacts with RIPK2 (PubMed:10880512, PubMed:17054981). Interacts with ARHGEF2 (PubMed:19043560). Interacts with NLRP10 and recruits it to the cell membrane following invasive bacterial infection (PubMed:22672233). Interacts with RNF34 (PubMed:25012219). Interacts with IFIH1; this interaction promotes transcription of antiviral genes and inhibition of viral replication (PubMed:32169843). Detected in the cytoplasm and at the cell membrane. Following bacterial infection, localizes to bacterial entry sites in the cell membrane. Recruited to the basolateral and apical membranes in polarized epithelial cells. Highly expressed in adult heart, skeletal muscle, pancreas, spleen and ovary. Also detected in placenta, lung, liver, kidney, thymus, testis, small intestine and colon. Palmitoylated. Palmitoylation is required for proper recruitment to the bacterial entry site and hence for proper signaling upon cognate peptidoglycan detection. Ubiquitinated. 'Lys-48'-linked polyubiquitination by RNF34 promotes proteasomal degradation and thereby negatively regulates NOD1 for instance in NF-kappa-B activation.