Phosphoglucomutase (EC 5.4.2.2;) is an enzyme that creates a glucose isomer by changing the site of the phosphate ion.

After glycogen phosphorylase has broken off a single glucose molecule from the greater glycogen structure, the free glucose has a phosphate group on its 1-carbon. This glucose-1-phosphate isomer cannot be metabolized easily. The enzyme phosphoglucomutase phosphorylates the 6-carbon, while subsequently dephosphorylating the 1-carbon. The result is glucose-6-phosphate, which can now theoretically travel down the glycolysis or pentose phosphate pathway.