Catalyzes the hydrolysis of fructose 1,6-bisphosphate to fructose 6-phosphate in the presence of divalent cations, acting as a rate-limiting enzyme in gluconeogenesis. Plays a role in regulating glucose sensing and insulin secretion of pancreatic beta-cells. Appears to modulate glycerol gluconeogenesis in liver. Important regulator of appetite and adiposity; increased expression of the protein in liver after nutrient excess increases circulating satiety hormones and reduces appetite-stimulating neuropeptides and thus seems to provide a feedback mechanism to limit weight gain. beta-D-fructose 1,6-bisphosphate + H2O = beta-D-fructose 6-phosphate + phosphate Binds 3 Mg(2+) ions per subunit. Subject to complex allosteric regulation. The enzyme can assume an active R-state, or an inactive T-state. Intermediate conformations may exist. AMP acts as allosteric inhibitor. AMP binding affects the turnover of bound substrate and not the affinity for substrate. Fructose 2,6-bisphosphate acts as competitive inhibitor. Fructose 2,6-bisphosphate and AMP have synergistic effects (By similarity). Carbohydrate biosynthesis; gluconeogenesis. Homotetramer. Belongs to the FBPase class 1 family.