GlmM is a bacterial phosphoglucosamine mutase (PNGM) that belongs to the alpha-D-phosphohexomutase superfamily. It is required for the interconversion of glucosamine-6-phosphate and glucosamine-1-phosphate in the biosynthetic pathway of UDP-N-acetylglucosamine, an essential precursor to components of the cell envelope. In order to be active, GlmM must be phosphorylated, which can occur via autophosphorylation or by the Ser/Thr kinase StkP. GlmM functions in a classical ping-pong bi-bi mechanism with glucosamine-1,6-diphosphate as an intermediate. Other members of the alpha-D-phosphohexomutase superfamily include phosphoglucosamine mutase (PNGM), phosphoacetylglucosamine mutase (PAGM), the bacterial phosphomannomutase ManB, and the bifunctional phosphomannomutase/phosphoglucomutase (PMM/PGM). Each of these enzymes has four domains with a centrally located active site formed by four loops, one from each domain. All four domains are included in this alignment model.