Interleukin-18 Receptor Beta (IL18R Beta)

Interleukin 18 receptor accessory protein is an accessory subunit of the heterodimeric receptor for IL18. This protein enhances the IL18 binding activity of IL18R1 (IL1RRP), a ligand binding subunit of IL18 receptor. The coexpression of IL18R1 and this protein is required for the activation of NF-kappa B and MAPK8 (JNK) in response to IL18. IL18RAP is predicted to contain a 14-amino acid signal peptide, a 342-amino acid extracellular (Ig superfamily-like) segment, a single transmembrane region, and a 222-amino acid cytoplasmic domain that is 32% identical to IL1R1. Northern blot analysis revealed that IL18RAP mRNA, present predominantly as a 3.8-kb product, was expressed strongly in peripheral blood leukocytes, spleen, lung, and, to a lesser extent, in colon, but not in any other tissue tested.