IL10RB is a single- pass type I membrane protein and contains two fibronectin type-III domains. It is an accessory chain which is essential for the active interleukin 10 receptor complex. Coexpression of IL10RB and IL10RA proteins has been shown to be required for IL10-induced signal transduction. Defects in IL10RB are the cause of inflammatory bowel disease type 25 (IBD25) which is a chronic, relapsing inflammation of the gastrointestinal tract with a complex etiology.