Phosphoglucomutase (EC number|22.214.171.124) is an
enzymethat transfers a phosphoryl groupon a glucose monomerfrom the 1' to the 6' position in the forward direction or the 6' to the 1' position in the reverse.
More specifically, it facilitates the interconversion of
glucose 1-phosphateand glucose 6-phosphate.
glycogen phosphorylasehas broken off a single glucosemolecule from the greater glycogenstructure, the free glucosehas a phosphategroup on its 1-carbon. This glucose-1-phosphate isomercannot be metabolized easily. The enzymephosphoglucomutase phosphorylates the 6-carbon, while subsequently dephosphorylating the 1-carbon. The result is glucose-6-phosphate, which can now theoretically travel down the glycolysisor pentose phosphate pathway.
Phosphoglucomutase also acts in the opposite fashion when a large concentration of glucose-6-phosphate is present. In this case, it is the 1-carbon that is phosphorylated and the 6-carbon that is dephosphorylated. The resulting glucose-1-phosphate is then changed into UDP-glucose in a number of intermediate steps. If activated by
insulin, glycogen synthasewill proceed to clip the glucose from the UDP-glucose complex and on to the glycogen molecule.
PGM1, PGM2, PGM3, PGM5
Wikimedia Foundation. 2010.