Enables interleukin-18 receptor activity. Involved in negative regulation of cold-induced thermogenesis. Acts upstream of or within several processes, including interleukin-18-mediated signaling pathway; positive regulation of NIK/NF-kappaB signaling; and positive regulation of interferon-gamma production. Predicted to be located in membrane. Predicted to be integral component of membrane. Predicted to be part of interleukin-18 receptor complex. Is expressed in dorsal aorta; gonad; mesonephros; and thymus primordium. Human ortholog(s) of this gene implicated in asthma. Orthologous to human IL18R1 (interleukin 18 receptor 1). [provided by Alliance of Genome Resources, Apr 2022]