beta-trefoil domain found in interleukin-37 (IL-37) and similar proteins
IL-37, also called FIL1 zeta, or IL-1X, or interleukin-1 family member 7, or IL-1F7, or interleukin-1 homolog 4, or IL-1H, or IL-1H4, or interleukin-1 zeta, or IL-1 zeta, or interleukin-1-related protein, or IL-1RP1, or interleukin-23, or IL-23, acts as a suppressor of innate inflammatory and immune responses involved in curbing excessive inflammation. This function requires SMAD3. It suppresses, or reduces, proinflammatory cytokine production, including IL1A and IL6, as well as CCL12, CSF1, CSF2, CXCL13, IL1B, IL23A, and IL1RN, but spares anti-inflammatory cytokines and inhibits dendritic cell activation. IL-37 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.",