Mechanisms and principles of N-linked protein glycosylation

N-linked glycosylation, a protein modification system present in all domains of life, is characterized by a high structural diversity of N-linked glycans found among different species and by a large number of proteins that are glycosylated. Based on structural, functional, and phylogenetic approaches, this review discusses the highly conserved processes that are at the basis of this unique general protein modification system.

► Protein N-linked glycosylation is a homologous process found both in eukaryotes and in prokaryotes.
► Prokaryotic N-glycan precursors are heterogeneous, whereas eukaryotes produce a conserved lipid-linked oligosaccharide structure.
► The N-X-S/T sequon is a unique acceptor sequence conserved in N-glycosylation.
► The specificity of oligosaccharyltransferase defines the complexity of the glycoproteome.