FGF domain, beta-trefoil fold, found in fibroblast growth factor 8 (FGF8) and similar proteins
FGF8, also called androgen-induced growth factor (AIGF), or heparin-binding growth factor 8 (HBGF8), plays an important role in the regulation of embryonic development, cell proliferation, cell differentiation, and cell migration. It is required for normal brain, eye, ear, and limb development during embryogenesis. It is also required for normal development of the gonadotropin-releasing hormone (GnRH) neuronal system. It plays a role in neurite outgrowth in hippocampal cells. FGF8 interacts with fibroblast growth factor receptors, FGFR1, FGFR2, FGFR3, and FGFR4. Affinity between fibroblast growth factors (FGFs) and their receptors is increased by heparan sulfate glycosaminoglycans that function as coreceptors. FGF8 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.