FGF domain, beta-trefoil fold, found in fibroblast growth factor 21 (FGF21) and similar proteins
FGF21 stimulates glucose uptake in differentiated adipocytes via the induction of glucose transporter SLC2A1/GLUT1 expression (but not SLC2A4/GLUT4 expression). Its activity requires the presence of beta-Klotho (KLB). It interacts (via C-terminus) with KLB and fibroblast growth factor receptor FGFR4. FGF21 contains a FGF domain with beta-trefoil fold, 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.