Glycoprotein

Glycoproteins may be defined as biopolymers having amino acids and sugar reduces link covalently to each other. They are widely distributed in nature. Found in higher animals, plants and microorganisms, glycoproteins contain a protein chain of any of the 20 naturally occurring L- α -amino acid units.

Proteoglycans are a subclass of glycoproteins with distinctive structure. Glycoproteins differ from monosaccharides protein structures in that they contain considerably less carbohydrate.

The mucopolysaccharides however may be considered a type of glycoprotein. Formed in the Golgi apparatus in the process of glycosylation, glycoproteins are important components of plasma membranes in which they extend throughout the lipid layer.

The molecular weights of glycoprotein range from 15,000 up to million. Some glycoproteins have only one glycochain in a molecule, whereas other glycoprotein possesses many glycochains in a molecule. The carbohydrate chains of glycoproteins are short, consisting perhaps eighth to ten saccharides units.

D-galactose, N-acetyl-D-galactosamine, D-glucose,  N-acetyl-D-glucosamine, D-mannose, L-fucose, and sialic acid, comprise the bulk of the carbohydrate moiety.
Glycoprotein