IL-1 R4

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-1 R family, SIGIRR (single Ig domain-containing IL-1 R-related molecule) differs from the other nine members by having only one Ig domain. ST2L, also known as IL-1 R4, is a transmembrane glycoprotein in the interleukin-1 receptor family. ST2L is expressed on mast cells and Th2 cells as well as on stressed cardiac myocytes and airway epithelia. ST2L associates with IL-1R AcP to form a receptor complex for IL-33. Alternative splicing generates ST2, a secreted isoform that functions as an inhibitor of IL-33 signaling. Within the ECD, mouse ST2L shares 68% aa sequence identity with human ST2L.