Glucose-6-phosphate isomerase, or phosphoglucose isomerase, is an enzyme () that catalyzes the conversion of glucose-6-phosphate into fructose-6-phosphate in the second step of glycolysis. An unrelated enzyme, D-xylose isomerase () catalyzes the isomerization of glucose to fructose, and is sometimes called "glucose isomerase".

The human variant of this enzyme is encoded by the GPI gene.

In glycolysis

As a glucose isomerase

Other functions

There is evidence that phosphoglucose isomerase acts as a molecular messenger. It is produced and secreted by white blood cells, and acts to regulate the growth of several different cell types.

es:Glucosa-6-fosfato isomerasa fr:Glucose isomérase ja:?????????????? zh:????????