Endosomal receptor that plays a key role in innate and adaptive immunity (PubMed:25297876, PubMed:32433612). Controls host immune response against pathogens through recognition of RNA degradation products specific to microorganisms that are initially processed by RNASET2 (PubMed:31778653). Recognizes GU-rich single- stranded RNA (GU-rich RNA) derived from SARS-CoV-2, SARS-CoV-1 and HIV- 1 viruses (PubMed:33718825). 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:23520111, PubMed:25599397, PubMed:26929371, PubMed:33718825). 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:16737960, PubMed:17932028, PubMed:29155428). {ECO:0000269|PubMed:16737960, ECO:0000269|PubMed:17932028, ECO:0000269|PubMed:23520111, ECO:0000269|PubMed:25297876, ECO:0000269|PubMed:25599397, ECO:0000269|PubMed:26929371, ECO:0000269|PubMed:29155428, ECO:0000269|PubMed:31778653, ECO:0000269|PubMed:32433612, ECO:0000269|PubMed:33718825}. This is the function of TLR8 (toll like receptor 8, ENSG00000101916).