Glycoproteins, N-Linked

Proteins that are either secreted from eukaryotic cells or expressed on their surfaces are usually modified with structures called asparagine-linked, or N-linked, oligosaccharides. These are short sugar polymers or glycans attached to the nitrogen atoms of asparaginyl residues. The resulting glycan-protein conjugates are termed N-linked glycoproteins. There are many different kinds of N-linked oligosaccharides with roles in a wide array of biological functions, and a basic knowledge of the pathways responsible for their synthesis is necessary to understand these functions. This article covers the key concepts behind the synthesis, structures, analysis, functions, and diseases of N-linked glycoproteins, and illustrates concepts with well-established examples from the literature.