Fructose-1,6-bisphosphatase class 2/Sedoheputulose-1,7-bisphosphatase (IPR004464)

Short name: FBPase_class-2/SBPase

Overlapping homologous superfamilies


Family relationships



Gluconeogenesis is an important metabolic pathway, which produces glucose from noncarbohydrate precursors such as organic acids, fatty acids, amino acids, or glycerol. Fructose-1,6-bisphosphatase, a key enzyme of gluconeogenesis, is found in all organisms, and five different classes of these enzymes have been identified.

This entry represents the class 2 fructose-1,6-bisphosphatases, which include GlpX and YggF of Escherichia coli (strain K12), which show different catalytic properties. The crystal structure of GlpX has been determined in a free state and in the complex with a substrate (fructose 1,6-bisphosphate) or inhibitor (phosphate). The crystal structure of the ligand-free GlpX revealed a compact, globular shape with two alpha/beta-sandwich domains. The core fold of GlpX is structurally similar to that of Li+-sensitive phosphatases suggesting that they have a common evolutionary origin and catalytic mechanism. The structure of the GlpX complex with fructose 1,6-bisphosphate revealed that the active site is located between two domains and accommodates several conserved residues coordinating two metal ions and the substrate. A third metal ion is bound to phosphate 6 of the substrate. Inorganic phosphate strongly inhibited activity of both GlpX and YggF, and the crystal structure of the GlpX complex with phosphate demonstrated that the inhibitor molecule binds to the active site. Alanine replacement mutagenesis of GlpX identifies 12 conserved residues important for activity and suggested that Thr(90) is the primary catalytic residue [PMID: 19073594].

A number of the proteins in this entry, particularly those from algae are bi functional and can catalyzes the hydrolysis of fructose 1,6-bisphosphate and sedoheptulose 1,7-bisphosphate to fructose 6-phosphate and sedoheptulose 7-phosphate, respectively.

GO terms

Biological Process

GO:0006094 gluconeogenesis
GO:0006071 glycerol metabolic process

Molecular Function

GO:0042132 fructose 1,6-bisphosphate 1-phosphatase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.