FIGURE 1.

The role cis-PTs in dolichol phosphate synthesis and protein glycosylation. A, DolP synthesis de novo in eukaryotic cell. Genes encoding enzymes involved in DolP synthesis in human cell are marked in red. DOLK, dolichol kinase. B, the role of heteromeric cis-PT in protein glycosylation. cis-PT generates polyprenol diphosphate on the cytoplasmic leaflet of the ER membrane. Polyprenol diphosphate is used as an intermediate in the synthesis of dolichol-linked saccharides (LLO). LLO is intermediate in protein N-glycosylation reactions. Dolichol-phosphate mannose (DolPMan) is also involved in O-mannosylation, glycosylphosphatidylinositol (GPI) anchor synthesis, and C-mannosylation. DolPGlc, dolichol-phosphate glucose; circled P, phosphorylation.