FGF domain, beta-trefoil fold, found in fibroblast growth factor 9 (FGF9) and similar proteins
FGF9, also called glia-activating factor (GAF), or heparin-binding growth factor 9 (HBGF-9), plays an important role in the regulation of embryonic development, cell proliferation, cell differentiation, and cell migration. It acts as a heparin-binding glia-activating factor that may have a role in glial cell growth and differentiation during development, gliosis during repair and regeneration of brain tissue after damage, differentiation and survival of neuronal cells, and growth stimulation of glial tumors. FGF9 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. FGF9 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.
Jiyao W et al.(2023). "The conserved domain database in 2023.",