N-linked glycosylation is a very prevalent form of glycosylation and is important for the folding of many eukaryotic glycoproteins and for cell&ndash;cell and cell&ndash;extracellular matrix attachment. The N-linked glycosylation process occurs in eukaryotes in the lumen of the endoplasmic reticulum and widely in archaea, but very rarely in bacteria. In addition to their function in protein folding and cellular attachment, the N-linked glycans of a protein can modulate a protein's function, in some cases acting as an on/off switch.