Phosphomannomutase 2 (PMM2)

Phosphomannomutase 2 catalyzes the isomerization of mannose 6-phosphate to mannose 1-phosphate. Mannose 1-phosphate is a precursor to GDP-mannose necessary for the synthesis of dolichol-P-oligosaccharides. Mutations in the gene have been shown to cause defects in the protein glycosylation pathway manifest as carbohydrate-deficient glycoprotein syndrome type I. By database searching for sequences similar to that of PMM1, Matthijs et al. (1997) identified identified and subsequently cloned a PMM2 cDNA. The deduced 246-amino acid PMM2 protein shares 66% and 57% sequence identity with PMM1 and yeast phosphomannomutase, respectively. Bjursell et al. (1998) achieved refined mapping of the PMM2 gene by analysis of radiation hybrids.