Within the IL18 receptor complex, does not mediate IL18-binding, but involved in IL18-dependent signal transduction, leading to NF-kappa-B and JNK activation (PubMed:9792649, PubMed:14528293, PubMed:25500532). May play a role in IL18-mediated IFNG synthesis from T-helper 1 (Th1) cells (Probable). H2O + NAD(+) = ADP-D-ribose + H(+) + nicotinamide Forms a ternary complex with IL18 and IL18R1 (PubMed:14528293, PubMed:25500532). Within this complex, IL18R1 is involved in ligand-binding and IL18RAP in signaling leading to NF-kappa-B and JNK activation (Probable). Detected in adrenal gland, bone marrow, brain, fetal brain, fetal liver, heart, kidney, lung, liver, peripheral blood leukocytes, placenta, prostate, salivary gland, skeletal muscle, spinal cord, testis, thymus, thyroid, trachea and uterus (PubMed:17897836). Strongly expressed in peripheral blood leukocytes and spleen and, to a lesser extent, in colon (PubMed:9792649). Specifically coexpressed with IL18R1 in T-helper 1 (Th1)cells (PubMed:10925275, PubMed:11046021, PubMed:10653850). Induced by IFN-alpha and IL12/interleukin-12 in natural killer (NK) cells and T-cells. The TIR domain mediates NAD(+) hydrolase (NADase) activity. Self-association of TIR domains is required for NADase activity. N-glycosylated. Belongs to the interleukin-1 receptor family.