Figure 1: Proteins acting within the NOD signaling pathway.

The recognistion of NOD1 and NOD2 of the bacterial peptidoglycan (PGN) promotes the formation of the multi-protein complex named inflammasome. The complex recruits the kinase receptor interacting protein 2 (RIP2), which is ubiquitinated by the ubiquitin ligases XIAP, BIRC2 and BIRC3 proteins. The polyubiquitinated RIP2 recruits the kinase TAK1 and TAK binding protein 1 (TAB1), TAB2 and TAB3 which leads to the activation of the MAPK kinases, p38 and c-Jun N-terminal kinase (JNK) through the activation of mitogen-activated protein kinase kinase (MKK). RIP2 polyubiquitinated also interacts with the IKK complex (IKKα, IKKβ and NEMO). The IKK complex mediates the phosphorylation of the IKKβ subunit of IKK by TAK1 and results in the phosphorylation and degradation of the NF-κB inhibitor (IκBα) which results in the cytoplasmic release and translocation of NF-κB dimers p65 and p50 in the nucleus to activate of the expression of the NF-κB proinflammatory genes.