<p>Phosphoglucomutases interconvert D-glucose 1-phosphate and D-glucose 6-phosphate, a reaction which is important for energy metabolism in many organisms and for cell wall biosynthesis in bacteria [<cite idref="PUB00028017"/>, <cite idref="PUB00028018"/>]. Beta-phosphoglucomutases are monomeric enzymes which interconvert the beta anomers of these compounds using Mg2+ as a cofactor.</p><p>This entry groups together three clades: the characterised beta-phosphoglucomutases (bPGMs) (including those from <taxon tax_id="562">Escherichia coli</taxon>, <taxon tax_id="1423">Bacillus subtilis</taxon> and <taxon tax_id="1358">Lactococcus lactis</taxon>, a clade of putative bPGMs from mycobacteria and a clade including the uncharacterised E. coli and <taxon tax_id="727">Haemophilus influenzae</taxon> yqaB genes which may prove to be beta-mutases of a related 1-phosphosugar. All of these are members of the larger Haloacid dehalogenase (HAD) subfamily IA and include the 'variant 3' Glu-Asp version of the third conserved HAD domain.</p><p>The Lactococcus enzyme has been crystallised and studied in detail [<cite idref="PUB00022122"/>]. It is composed of two distinct regions, an alpha/beta core domain similar to that found in other HAD family members, and a helical cap domain. The core domain contains a central six-stranded parallel beta sheet surrounded by six alpha helices, while the cap domain consists of an antiparallel four alpha-helix bundle. Overall, the monomer forms a "kidney-bean" shape similar to that observed in other HAD family members such as phosphoserine phosphatase. The active site of the enzyme is located at the interface of the two domains.</p>