Receptor for IL17A and IL17F, major effector cytokines of innate and adaptive immune system involved in antimicrobial host defense and maintenance of tissue integrity. Receptor for IL17A (PubMed:17911633, PubMed:9367539). Receptor for IL17F (PubMed:19838198, PubMed:17911633). Binds to IL17A with higher affinity than to IL17F (PubMed:17911633). Binds IL17A and IL17F homodimers as part of a heterodimeric complex with IL17RC (PubMed:16785495). Also binds heterodimers formed by IL17A and IL17F as part of a heterodimeric complex with IL17RC (PubMed:18684971). Cytokine binding triggers homotypic interaction of IL17RA and IL17RC chains with TRAF3IP2 adapter, leading to TRAF6-mediated activation of NF-kappa-B and MAPkinase pathways, ultimately resulting in transcriptional activation of cytokines, chemokines, antimicrobial peptides and matrix metalloproteinases, with potential strong immune inflammation (PubMed:16785495, PubMed:24120361, PubMed:17911633, PubMed:18684971, PubMed:21350122). Involved in antimicrobial host defense primarily promoting neutrophil activation and recruitment at infection sites to destroy extracellular bacteria and fungi (By similarity). In secondary lymphoid organs, contributes to germinal center formation by regulating the chemotactic response of B cells to CXCL12 and CXCL13, enhancing retention of B cells within the germinal centers, B cell somatic hypermutation rate and selection toward plasma cells (By similarity). Plays a role in the maintenance of the integrity of epithelial barriers during homeostasis and pathogen infection. Stimulates the production of antimicrobial beta-defensins DEFB1, DEFB103A, and DEFB104A by mucosal epithelial cells, limiting the entry of microbes through the epithelial barriers (By similarity). Involved in antiviral host defense through various mechanisms. Enhances immunity against West Nile virus by promoting T cell cytotoxicity. Contributes to Influenza virus clearance by driving the differentiation of B-1a B cells, providing for production of virus-specific IgM antibodies at first line of host defense (By similarity). Receptor for IL17C as part of a heterodimeric complex with IL17RE (PubMed:21993848). (Microbial infection) Receptor for SARS coronavirus-2/SARS-CoV-2 virus protein ORF8, leading to IL17 pathway activation and an increased secretion of pro-inflammatory factors through activating NF-kappa-B signaling pathway. Forms heterodimers with IL17RC; the heterodimer binds IL17A and IL17F homodimers as well as the heterodimer formed by IL17A and IL17F (PubMed:16785495, PubMed:18684971, PubMed:32187518). Forms complexes with 2:1 binding stoichiometry: two receptor chains for one interleukin molecule (PubMed:32187518). IL17A homodimer preferentially drives the formation of IL17RA-IL17RC heterodimeric receptor complex, whereas IL17F homodimer forms predominantly complexes with IL17RC homodimer (PubMed:32187518). IL17A homodimer adopts an asymmetrical ternary structure with one IL17RA molecule, allowing for high affinity interactions of one IL17A monomer with one IL17RA molecule (via D1 and D2 domains), while disfavoring binding of a second IL17RA molecule on the other IL17A monomer (PubMed:23695682). IL17A-IL17F forms complexes with IL17RA-IL17RC, but with lower affinity when compared to IL17A homodimer (PubMed:32187518). IL17RA chain cannot distinguish between IL17A and IL17F molecules, potentially enabling the formation of topologically distinct complexes (PubMed:28827714). Interacts with TRAF3IP2 (PubMed:24120361). Forms heterodimers with IL17RE; the heterodimer binds IL17C (PubMed:21993848, PubMed:16785495, PubMed:18684971). (Microbial infection) Interacts with SARS coronavirus-2/SARS-CoV-2 virus protein ORF8. Widely expressed. Glycosylated. The disease is caused by variants affecting the gene represented in this entry. Soluble isoform lacking the transmembrane segment.