The innate immune system recognizes microbial pathogens through Toll-like receptors (TLRs), which identify pathogen-associated molecular patterns. Different TLRs recognize different pathogen-associated molecular patterns and all TLRs have a Toll-interleukin 1 receptor (TIR) domain, which is responsible for signal transduction. The protein encoded by this gene is a TIR adaptor protein involved in the TLR4 signaling pathway of the immune system. It activates NF-kappa-B, MAPK1, MAPK3 and JNK, which then results in cytokine secretion and the inflammatory response. Alternative splicing of this gene results in several transcript variants; however, not all variants have been fully described. [provided by RefSeq, Jul 2008],function:Adapter involved in the TLR4 signaling pathway in the innate immune response. Acts via IRAK2 and TRAF-6, leading to the activation of NF-kappa-B, MAPK1, MAPK3 and JNK, resulting in cytokine secretion and the inflammatory response.,polymorphism:Genetic variation in TIRAP can influence susceptibility or resistance to invasive pneumococcal disease, bacteremia, malaria and tuberculosi.,similarity:Contains 1 TIR domain.,subunit:Homodimer. Also forms heterodimers with MyD88. Binds to TLR4 and IRAK2 via their respective TIR domains. Binds to PKR and TBK1. Does not interact with IRAK1, nor TLR9.,tissue specificity:Highly expressed in liver, kidney, spleen, skeletal muscle and heart. Also detected in peripheral blood leukocytes, lung, placenta, small intestine, thymus, colon and brain.,