N-linked oligosaccharides can link covalently to proteins at Asparagine (Asn) amino acid.
N-linked oligosaccharides link with polypeptide chain to form glycoprotein. This reaction is referred as N-glycosylation. The sugar moiety attaches to the nitrogen (N) of the amide side chain of Asparagine.
Glycoproteins are membrane proteins that play role in cell to cell interaction.