What is the Difference Between N-linked and O-linked Oligosaccharides?

The main difference between N-linked and O-linked oligosaccharides lies in the type of amino acid residues to which the sugar is attached. N-linked oligosaccharides are attached to an asparagine (N) residue, while O-linked oligosaccharides are attached to a serine or threonine (O) residue. Here are some key differences between N-linked and O-linked oligosaccharides:

1. Amino Acid Residues: N-linked glycosylation connects the sugar to an asparagine (N) residue, while O-linked glycosylation prefers a serine or threonine (O) residue.
2. Core Structure: N-linked sugars adopt the high mannose type core structure, whereas O-linked sugars offer a more extensive range of core structures, including core 1, core 2, and core 3.
3. Glycan Linkages: In N-linked glycosylation, a protein can exhibit multiple glycan linkages ranging from one to many. In contrast, O-linked glycosylation typically includes only a single sugar residue added to a serine or threonine.
4. Glycosylation Process: Both N-linked and O-linked glycosylation are highly regulated processes, and there are several cases in which these two pathways can cross-regulate each other. For example, O-linked glycosylation can affect the efficiency and specificity of N-linked glycosylation.

In summary, N-linked and O-linked oligosaccharides differ in the type of amino acid residues they are attached to, their core structures, the number of glycan linkages, and the ways in which their glycosylation processes are regulated.

Comparative Table: N-linked vs O-linked Oligosaccharides

The main difference between N-linked and O-linked oligosaccharides lies in the type of amino acid residue to which the sugar is attached and the core structure of the oligosaccharide itself. Here is a comparison table highlighting the differences between N-linked and O-linked oligosaccharides:

N-linked oligosaccharides are carbohydrate molecules where an oligosaccharide is attached to an asparagine residue, while O-linked oligosaccharides are a type of carbohydrates where a sugar molecule is attached to an oxygen atom of a serine or threonine residue.