IL-33R, also known as ST2, is a receptor for IL-33. It is a member of the IL-1 receptor family of innate receptors. Its extracellular domain consists of 3 Ig-like domains that directly interact with its co-receptor IL-1RAcP, and the ligand alarmin, IL-33. IL-33 ligation results in the association of IL-33R complex with its adaptor proteins MyD88, IRAK1, IRAK4 and TRAF6, and activation of the NF-kB, and MAPK pathways. This, in turn, instigates the release of chemokines and cytokines such as IL-5, IL-6, IL-8, and IL-13. Two most common isoforms of IL-33R that result from alternative splicing are ST2L – the membrane bound form, and ST2S – the soluble form. The membrane bound form can be released from the cell surface by proteolytic cleavage. The soluble forms have been suggested to act as decoys dampening the IL-33 signaling. IL-33R is primarily expressed by mast cells, basophils, and eosinophils. In mouse, IL-33R expression has been shown on ILC2 and Th2 cells. IL-33R signaling has been implicated in the number of immune conditions, including allergies, arthritis, atherosclerosis and sepsis.
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Protein Aliases: Fit-1; Fos-responsive gene 1 protein; growth stimulation-expressed; homolog of mouse growth stimulation-expressed; IL-1 R4; IL-1RL1; IL-33R; interleukin 1 receptor-like 1; interleukin 1 receptor-related protein; Interleukin-1 receptor-like 1; Interleukin-33 receptor alpha chain; Interleukin1 receptor like 1; Lymphocyte antigen 84; Protein ST2; Protein T1; sIL 33R; soluble IL 33 Receptor; soluble IL 33R
Gene Aliases: DER4; FIT-1; FIT1; IL1RL1; IL33R; Ly84; ST2; St2-rs1; ST2L; ST2V; Ste2; T1; T1/ST2
Molecular Function: transmembrane signal receptor