Enables interleukin-33 binding activity and interleukin-33 receptor activity. Involved in several processes, including negative regulation of T-helper 1 type immune response; positive regulation of macrophage activation; and regulation of cytokine production. Acts upstream of or within negative regulation of I-kappaB kinase/NF-kappaB signaling. Located in external side of plasma membrane and extracellular matrix. Is expressed in several structures, including immune system; musculoskeletal system; salivary gland; skin; and visual system. Human ortholog(s) of this gene implicated in asthma and coronary artery disease. Orthologous to human IL1RL1 (interleukin 1 receptor like 1). [provided by Alliance of Genome Resources, Apr 2022]