Glucose-6-phosphatase is an enzyme of gluconeogenesis that catalyzes the hydrolysis of glucose-6-phosphate (G6P) to glucose plus Pi.

G6P + H2O <=> Glucose + Pi

Activity of the enzyme is regulated, not allosterically, but rather by the concentration of the substrate, G6P. Normally the concentration of G6P is considerably lower than the KM of the enzyme.

Glucose-6-phosphatase is an important enzyme for making glucose from G6P in tissues, such as liver and kidney, that supply glucose to other tissues via the bloodstream. The enzyme is not made appreciably in muscles, which obtain glucose for use in glycolysis either from the bloodstream or as G6P from glucose-1-phosphate produced during glycogen catabolism. The enzyme has been implicated in von Gierke's disease, a glycogen storage disorder (see here).