Proteoglycan

A proteoglycan is a glycoconjugate formed from a protein bound to one or more glycosaminoglycan chains (polysaccharide). The carbohydrate part of a proteoglycan can make up to 95% of the molecular weight of the molecule.

Proteoglycans are produced by glycosylation of proteins in the Golgi apparatus and endoplasmic reticulum. They are either incorporated into the plasma membrane or are excreted.