The synthesis of dolichyl-phosphate mannose occurs on the cytosolic side of the endoplasmic reticulum (ER). It then translocates to the lumen side of the ER where it acts as a mannose donor in several processes, including the synthesis of dolichol-linked oligosaccharide (LLO) precursor (protein N-glycosylation), protein O-mannosylation, protein C-glycosylation and the synthesis of the glycosyl phosphatidylinositol (GPI) anchor precursor. (Adapted from PMID:28616799 and FBrf0254674.)