Endosomal receptor that plays a key role in innate and adaptive immunity (PubMed:14976261, PubMed:32433612). Controls host immune response against pathogens through recognition of uridine-containing single strand RNAs (ssRNAs) of viral origin or guanosine analogs (PubMed:31608988, PubMed:27742543, PubMed:12738885, PubMed:32706371). Upon binding to agonists, undergoes dimerization that brings TIR domains from the two molecules into direct contact, leading to the recruitment of TIR-containing downstream adapter MYD88 through homotypic interaction (PubMed:27742543). In turn, the Myddosome signaling complex is formed involving IRAK4, IRAK1, TRAF6, TRAF3 leading to activation of downstream transcription factors NF-kappa-B and IRF7 to induce pro-inflammatory cytokines and interferons, respectively (PubMed:27742543, PubMed:32706371). Activated by guanosine analogs including deoxyguanosine, 7-thia-8-oxoguanosine or 7-deazaguanosine in a RNA-independent manner. Activated by imiquimod (PubMed:32706371). Homodimer (PubMed:27742543). Interacts with MYD88 via their respective TIR domains (Probable). Interacts with UNC93B1 (PubMed:33432245). Interacts with SMPDL3B (By similarity). Relocalizes from endoplasmic reticulum to endosome and lysosome upon stimulation with agonist. Detected in brain, placenta, spleen, stomach, small intestine, lung and in plasmacytoid pre-dendritic cells. Expressed in peripheral mononuclear blood cells (PubMed:32706371). Contains two binding domains, first site for small ligands and second site for ssRNA. The disease is caused by variants affecting the gene represented in this entry. Belongs to the Toll-like receptor family.