During the N-glycosylation process, a preassembled oligosaccharide (Glc[[3]]Man[[9]]GlcNAc[[2]]) is transferred from a lipid carrier (dolichol pyrophosphate, PP-Dol) to an acceptor protein. Dolichyl pyrophosphate glucosyltransferases act in the final step of N-glycan precursor synthesis within the endoplasmic reticulum, adding the three glucose units (Glc[[3]]). The finished oligosaccharide is then transferred to nascent peptides, where it will be further trimmed down and modified to produce glycoproteins. (Adapted from FBrf0235108.)