This enzyme participates in both the breakdown and synthesis of glucose. alpha-D-glucose 1-phosphate = alpha-D-glucose 6-phosphate Binds 1 Mg(2+) ion per subunit. Glucose-1,6-bisphosphate enhances phosphorylation of the active site Ser-117, and thereby increases enzyme activity. Monomer. Phosphorylation at Thr-467 by PAK1 significantly enhances enzymatic activity. Many polymorphic variants of PGM1 exist. 8 different alleles are known: PGM1*1+, PGM1*1-, PGM1*2+, PGM1*2-, PGM1*3+, PGM1*3-, PGM1*7+ and PGM1*7-. The sequence of PGM1*1+ is shown here. The disease is caused by variants affecting the gene represented in this entry. Belongs to the phosphohexose mutase family. Truncated N-terminus.