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 (By similarity). Carbohydrate biosynthesis; gluconeogenesis. Homotetramer. Belongs to the FBPase class 1 family.