Dolichol is a polyisoprenol lipid composed of isoprene units linked in a head-to-tail manner where the length of the isoprenol chain is species specific. The biosynthesis of dolichyl phosphate (DolP), the main dolichol derivative, occurs on the cytosolic face of the endoplasmic reticulum membrane beginning with the precursor (2E,6E)-farnesyl diphosphate. DolP can also be generated by the de-phosphorylation of dolichyl diphosphate released after the transfer of the N-glycan oligosaccharide precursor to proteins during protein N-glycosylation. DolP acts as a lipid carrier for the synthesis of the oligosaccharide precursor used for protein N-glycosylation and for the lipid and protein glycosylation sugar donors dolichyl-phosphate mannose and dolichyl-phosphate glucose. (Adapted from PMID:38821050 and PMID:21384228.)