fosfoglukomutaz

Fosfoglukomutaz, or phosphoglucomutase (PGM), is a cytosolic enzyme that catalyzes the reversible conversion between glucose-1-phosphate (G1P) and glucose-6-phosphate (G6P). It belongs to the phosphoglucomutase family and is classified as EC 5.4.2.2. The enzyme enables interconversion of sugar phosphates required for glycogen breakdown and for entry of glucose into central metabolism.

There are two major enzyme families: cofactor-dependent phosphoglucomutases (dPGM) and cofactor-independent phosphoglucomutases (iPGM). dPGM uses a Mg2+ ion and proceeds via a phosphoserine intermediate (phosphorylated serine) in a “ping-pong” mechanism. iPGM has a different catalytic strategy and does not require the phosphoserine intermediate; it typically relies on a metal-activated center.

In humans and many eukaryotes, the canonical enzyme is PGM1, which catalyzes G1P ↔ G6P and links glycogenolysis, glycolysis, and the galactose pathway to UDP-glucose synthesis via the UDP-glucose pyrophosphorylase reaction when G1P is available. In bacteria and archaea, both dPGM and iPGM variants are found, showing diversity in mechanism and regulation.

Localization is cytosolic in most cells; the enzyme is generally constitutively expressed, with activity modulated by metal ion availability and, for the dPGM class, by phosphorylation state of the active-site serine.

Mutations in human PGM1 can lead to metabolic and glycosylation disorders. Synonyms include phosphoglucomutase, PGM, GPM, and fosfoglukomutaz in some languages.