<p>Phosphoglycerate mutase (<db_xref db="EC" dbkey="5.4.2.1"/>) (PGAM) and bisphosphoglycerate mutase (<db_xref db="EC" dbkey="5.4.2.4"/>) (BPGM) are structurally related enzymes that catalyse reactions involving the transfer of phospho groups between the three carbon atoms of phosphoglycerate [<cite idref="PUB00000183"/>, <cite idref="PUB00001554"/>, <cite idref="PUB00007922"/>]. Both enzymes can catalyse three different reactions with different specificities, the isomerization of 2-phosphoglycerate (2-PGA) to 3-phosphoglycerate (3-PGA) with 2,3-diphosphoglycerate (2,3-DPG) as the primer of the reaction, the synthesis of 2,3-DPG from 1,3-DPG with 3-PGA as a primer and the degradation of 2,3-DPG to 3-PGA (phosphatase <db_xref db="EC" dbkey="3.1.3.13"/> activity).</p><p>In mammals, PGAM is a dimeric protein with two isoforms, the M (muscle) and B (brain) forms. In yeast, PGAM is a tetrameric protein.</p> <p>BPGM is a dimeric protein and is found mainly in erythrocytes where it plays a major role in regulating haemoglobin oxygen affinity as a consequence of controlling 2,3-DPG concentration. The catalytic mechanism of both PGAM and BPGM involves the formation of a phosphohistidine intermediate [<cite idref="PUB00003558"/>].</p> <p> A number of other proteins including, the bifunctional enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase [<cite idref="PUB00004695"/>] that catalyses both the synthesis and the degradation of fructose-2,6-bisphosphate and bacterial alpha-ribazole-5'-phosphate phosphatase, which is involved in cobalamin biosynthesis, belong to this family [<cite idref="PUB00002873"/>].</p><p>This entry contains the active site phosphohistidine residue.</p>