Description
IL1 is a name that designates two pleiotropic cytokines, IL1µ (IL1F1) and IL1µ (IL1F2), which are the products of distinct genes. IL1µ and IL1µ are structurally related polypeptides that share approximately 21% amino acid (aa) identity in human. Both proteins are produced by a wide variety of cells in response to inflammatory agents, infections, or microbial endotoxins. While IL1µ and same receptor and exert identical biological effects. IL1 RI binds directly to IL1µ or IL1µ and then associates with IL1 R accessory protein (IL1 R3/IL1 R AcP) to form a highaffinity receptor complex that is competent for signal transduction. IL1 RII has high affinity for IL1µ but functions as adecoy receptor and negative regulator of IL1µ activity. IL1ra functions as a competitive antagonist by preventing IL1µ and IL1µ from interacting with IL1 RI. The human IL1µ cDNA encodes a 269 aa precursor. A 116 aa propeptide is cleaved intracellularly by the cysteine protease IL1µconverting enzyme (Caspase1/ICE) to generate the active cytokine