This product recognizes the Single Ig IL-1-related receptor (SIGIRR), a member of the Toll-like receptor-interleukin 1 receptor superfamily, defined by an intracellular Toll-IL-1R (TIR) domain. SIGIRR acts as a negative regulator of the Toll-like and IL-1R receptor signalling pathways. It interacts with TLR4, TLR5, TLR9 and IL-1R through the extracellular Ig domain, or the intracellular TIR domain. The Ig domain interferes with the heterodimerisation of IL-1R while the intracellular TIR domain inhibits both IL-1 and LPS signalling by attenuating the recruitment of receptor-proximal signalling components to TLR4. SIGIRR is expressed in kidney, colon, small intestine, lung, spleen and liver. It is not expressed in brain and muscle.