High Quality Content by WIKIPEDIA articles! Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) also known as caspase recruitment domain-containing protein 15 (CARD15) or inflammatory bowel disease protein 1 (IBD1) is a protein that in humans is encoded by the NOD2 gene located on chromosome 16. NOD2 plays an important role in the immune system. It recognizes bacterial molecules (peptidoglycans) and stimulates an immune reaction. Mutations in NOD2 are associated with autoimmune diseases.