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 2 (IL1RAPL2), also known as TIGIRR1, is a member of the IL-1 RI-like family of the IL-1R/Toll-like receptor superfamily. IL1RAPL2 is a type I transmembrane protein that contains three Ig-like domains in its extracellular region and one intracellular TIR domain. IL1RAPL2 is expressed in the central nervous system, and its deletion is associated with some forms of X-linked mental retardation. An alternately spliced variant lacks the transmembrane and cytoplasmic regions. Within their extracellular domains, mouse IL1RAPL2 shares 99% amino acid sequence identity with human IL1RAPL2.
