N-linked glycans are attached to which amino acid in naturally occurring glycoproteins?

N-linked glycans are attached to which amino acid in naturally occurring glycoproteins?

• A. Serine
• B. Asparagine
• C. Threonine
• D. Lysine

Answer: (B)

N-linked glycosylation attaches a preassembled oligosaccharide to the amide nitrogen of an asparagine residue within a protein, usually in the ER during synthesis. This modification occurs specifically at Asn residues in the consensus sequence Asn-X-Ser/Thr, where X is any amino acid except proline, and the glycan forms a nitrogen–glycosidic bond with the asparagine side chain. This is distinct from O-linked glycosylation, which occurs on the hydroxyl groups of serine or threonine. So the amino acid bearing the N-linked glycan is asparagine.

N-linked glycosylation attaches a preassembled oligosaccharide to the amide nitrogen of an asparagine residue within a protein, usually in the ER during synthesis. This modification occurs specifically at Asn residues in the consensus sequence Asn-X-Ser/Thr, where X is any amino acid except proline, and the glycan forms a nitrogen–glycosidic bond with the asparagine side chain. This is distinct from O-linked glycosylation, which occurs on the hydroxyl groups of serine or threonine. So the amino acid bearing the N-linked glycan is asparagine.