Dimerization effect of sucrose octasulfate on rat FGF1

Fibroblast growth factors (FGFs) constitute a family of at least 23 structurally related heparin‐binding proteins that are involved in regulation of cell growth, survival, differentiation and migration. Sucrose octasulfate (SOS), a chemical analogue of heparin, has been demonstrated to activate FGF signalling pathways. The structure of rat FGF1 crystallized in the presence of SOS has been determined at 2.2 Å resolution. SOS‐mediated dimerization of FGF1 was observed, which was further supported by gel‐filtration experiments. The major contributors to the sulfate‐binding sites in rat FGF1 are Lys113, Lys118, Arg122 and Lys128. An arginine at position 116 is a consensus residue in mammalian FGF molecules; however, it is a serine in rat FGF1. This difference may be important for SOS‐mediated FGF1 dimerization in rat.