Adapter protein involved in the Toll-like receptor and IL-1 receptor signaling pathway in the innate immune response. Acts via IRAK1, IRAK2, IRF7 and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response. Increases IL-8 transcription. Involved in IL-18-mediated signaling pathway. Activates IRF1 resulting in its rapid migration into the nucleus to mediate an efficient induction of IFN-beta, NOS2/INOS, and IL12A genes. Homodimer. Also forms heterodimers with TIRAP. Binds to TLR2, TLR4, IRAK1, IRAK2 and IRAK4 via their respective TIR domains. Interacts with IL18R1. Interacts with BMX, IL1RL1 and IRF7. Interacts with LRRFIP1 and LRRFIP2; this interaction positively regulates Toll-like receptor (TLR) signaling in response to agonist. Interacts with FLII. LRRFIP1 and LRRFIP2 compete with FLII for MYD88-binding. Interacts with IRF1. Ubiquitous. 4 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.