Adapter protein involved in the Toll-like receptor and IL-1 receptor signaling pathway in the innate immune response (PubMed:15361868, PubMed:18292575, PubMed:33718825, PubMed:37971847). Acts via IRAK1, IRAK2, IRF7 and TRAF6, leading to NF-kappa-B activation, cytokine secretion and the inflammatory response (PubMed:15361868, PubMed:19506249, PubMed:24316379, PubMed:40638072). Increases IL-8 transcription (PubMed:9013863). 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. Upon TLR8 activation by GU-rich single-stranded RNA (GU-rich RNA) derived from viruses such as SARS- CoV-2, SARS-CoV and HIV-1, induces IL1B release through NLRP3 inflammasome activation (PubMed:33718825). MyD88-mediated signaling in intestinal epithelial cells is crucial for maintenance of gut homeostasis and controls the expression of the antimicrobial lectin REG3G in the small intestine (By similarity). {ECO:0000250|UniProtKB:P22366, ECO:0000269|PubMed:15361868, ECO:0000269|PubMed:18292575, ECO:0000269|PubMed:19506249, ECO:0000269|PubMed:20855887, ECO:0000269|PubMed:24316379, ECO:0000269|PubMed:33718825, ECO:0000269|PubMed:37971847, ECO:0000269|PubMed:40638072, ECO:0000269|PubMed:9013863}. This is the function of Ensembl gene identifier ENSG00000172936 (MYD88, MYD88 innate immune signal transduction adaptor).