The Interleukin 1 receptor family comprises at least nine members. All family members possess three immunoglobulin (Ig)-like domains in their extracellular region. Most members also have an intracellular TIR (Toll-like receptor/IL-1 receptor) signaling domain that is also conserved in the Toll-like receptor family. A subtype of the IL-1R family, SIGIRR (single Ig domain-containing IL-1 R-related molecule) differs from the other nine members by having only one Ig domain.
Interleukin 1 receptor accessory protein-like 1 (IL1RAPL1), also known as Oligophrenin-4 (OPHN4) and three immunoglobulin domain containing IL-1 receptor-related 2 (TIGIRR2), is a member of the IL-1 receptor superfamily.
