Dolichol Phosphate-Mannose Synthase (DPM1 and DPM2)
Dolichol phosphate-mannose synthase (Dol-P-Man synthase), which generates dolichol phosphate-mannose (Dol-P-Man) from GDP-mannose (GDP-Man) and dolichol phosphate (Dol-P), is an essential enzyme for all eukaryotic cells. The Dol- P-Man synthase is located in the endoplasmic reticulum (ER), through two kinds of binding to the membrane depending on the species (Colussi et al. 1997; Maeda et al. 1998). One group comprises Saccharomyces cerevisiae, Ustilago maydis, and Trypanosoma brucei enzymes, which have a C-terminal hydrophobic domain; and the other group includes the human, mouse, Schizosaccharomyces pombe, and Caenorhabditis briggsiae synthases, which lack a C-terminal hydrophobic domain. In the latter group, at least two polypeptides form the Dol-P-Man synthase complex, where the catalytic subunit DPMI binds to the membrane protein DPM2, which has two membrane spanning regions (Maeda et al. 1998). The Dol-P-Man synthesized by Dol-P-Man synthase is used for the five mannose moieties of N-linked oligosaccharide, the first mannose moiety of fungal O-linked oligosaccharide, three mannose moieties of glycosyl phosphatidylinositol (GPI) anchoring, and C-mannosylation (Orlean 1990; Doucey et al. 1998). Recently, a deficiency of the DPM1 gene was found to cause a congenital disorder of glycosylation (CDG) type Ie, giving rise to mental and psychomotor retardation, dysmorphism, and blood coagulation defects.
KeywordsSchizosaccharomyces Pombe Phosphate Mannose Trypanosoma Brucei Membrane Span Region Lipid Intermediate
Unable to display preview. Download preview PDF.