beta-trefoil domain found in interleukin-1 receptor antagonist protein (IL-1RA) and similar proteins
IL-1RA, also called IL-1RN, or IRAP, or ICIL-1RA, or IL1 inhibitor, inhibits the activity of interleukin-1 (IL-1) by binding to receptor IL1R1 and preventing its association with the co-receptor IL1RAP for signaling. It has no IL-1 like activity. IL-1RN binds functional interleukin-1 receptor IL1R1 with greater affinity than decoy receptor IL1R2; however, the physiological relevance of the latter association is unknown. IL-1RN contains a beta-trefoil domain, which is characterized by 12 beta strands folded into three similar trefoil subdomains (alpha, beta, and gamma) associated to give an overall structure with pseudo-3-fold symmetry.
Jiyao W et al.(2023). "The conserved domain database in 2023.",