|Glycoprotein is s protein with oligosaccharide chains (glycans) covalently attached to their polypeptide side chain.
|Proteoglycans are a subclass of glycoproteins. Proteoglycan consists of a core protein with one or more covalently attached glycosaminoglycan (GAG) chain(s).
|Glycoprotein’s carbohydrates chain is relatively short. The chains are often branched instead of linear, and may or may not negatively charged.||The chains are long, linear carbohydrate polymers that are negatively charged under physiological conditions, due to the occurrence of sulfate and uronic acid groups.|
|There are two broad categories of glycoprotein – N-linked or O-linked saccharides.||Proteoglycans can be categorized depending upon the nature of their glycosaminoglycan chains.|
|Glycoproteins are found on cell surfaces. Most of them are integral membrane proteins, with carbohydrates attached to the peptide chains that are outside of the cell.||Proteoglycans are found mainly in connective tissues. They contribute to the organization and physical properties of the extracellular matrix.|
|Glycoproteins function in cell-cell recognition. Examples: ABO blood group antigens.||Proteoglycan function in modulation of cell growth processes or cushioning in joints.
Examples: mucoproteins in extracellular matrix, chondroitin sulphate in cartilages and some other materials in connective tissues.