InterPro: IPR000146 Fructose-1,6-bisphosphatase

This entry represents fructose-1,6-bisphosphatase (FBPase), a critical regulatory enzyme in gluconeogenesis that catalyses the removal of 1-phosphate from fructose 1,6-bis-phosphate to form fructose 6-phosphate [1, 2]. It is involved in many different metabolic pathways and found in most organisms. FBPase requires metal ions for catalysis (Mg²⁺ and Mn²⁺ being preferred) and the enzyme is potently inhibited by Li⁺. The fold of fructose-1,6-bisphosphatase was noted to be identical to that of inositol-1-phosphatase (IMPase) [3]. Inositol polyphosphate 1-phosphatase (IPPase), IMPase and FBPase share a sequence motif (Asp-Pro-Ile/Leu-Asp-Gly/Ser-Thr/Ser) which has been shown to bind metal ions and participate in catalysis. This motif is also found in the distantly-related fungal, bacterial and yeast IMPase homologues. It has been suggested that these proteins define an ancient structurally conserved family involved in diverse metabolic pathways, including inositol signalling, gluconeogenesis, sulphate assimilation and possibly quinone metabolism [4].