IL17RA (Interleukin 17 receptor A), also known as IL17R and CDw217, is a ubiquitous type I membrane glycoprotein that binds with low affinity to interleukin 17A (IL17A). IL17A and its receptor play a pathogenic role in many inflammatory and autoimmune diseases such as rheumatoid arthritis. IL17A binds to a type I cell surface receptor called IL17R of which there are at least three variants IL17RA, IL17RB, and IL17RC. IL17RA is a widely expressed glycoprotein that plays a central role in inflammatory responses. Within the extracellular domain, human IL17RA shares 72% aa sequence identity with mouse and rat IL17RA. IL17RA associates with IL17RC to form a signaling receptor complex for IL17 and IL17F. Ligand and IL17RA ligation promotes T cell activation and the production of IL-6, G-CSF, SCF, and multiple proinflammatory chemokines