Protein N-linked glycosylation is a co- and post-translational modification involving the attachment of an oligosaccharide to the amino group of asparagine (Asn) residues within specific consensus sequences via a N-glycosidic bond. It begins in the endoplasmic reticulum with the synthesis of a dolichol-linked precursor oligosaccharide (Glc(3)Man(9)GlcNAc(2)), which is transferred to Asn residues in acceptor proteins by the oligosaccharyl transferase complexes during (and shortly after) their synthesis. This N-glycan precursor is then trimmed by glucosidases and mannosidases to produce oligomannose-type N-glycans. These structures can be further modified in the Golgi by various glycosidases and glycosyltransferases resulting in the production of hybrid, paucimannose and complex-type N-glycans. Following N-glycan processing, the glycoproteins are transported to organelles, the plasma membrane and secreted. In D. melanogaster, N-linked glycans are predominantly composed of high and paucimannose structures that may be fucosylated on the GlcNAc core, and a relatively low amount of hybrid and complex glycans. N-linked glycans are essential for a wide variety of biological processes, such as protein folding, cellular targeting and motility, and the immune response. (Adapted from FBrf0235108.)