Structure, Metabolism, and Tissue Roles of Chondroitin Sulfate Proteoglycans

Abstract

Proteoglycans (PGs) are a complex group of glycoproteins that are characterized by the presence of one or more sulfated glycosaminoglycan (GAG) chains and various oligosaccharides that are covalently attached to a core protein. The majority of chondroitin sulfate proteoglycans (CSPGs) belongs to the group of large aggregating PGs (hyalectins) and small leucine-rich PGs. The sulfated GAG chains, oligosaccharides, and domains within the core proteins of these macromolecules allow PGs to interact with a large number of macromolecules. As a result, PGs have wide‐ranging roles in tissues where they are involved in the organization and function of extracellular matrices, matrix cell interactions, and the regulation of cellular processes. The cellular and tissue location of PGs is largely dependent on the interactions of specific domains in the core proteins and the GAG chains with other molecules present in the cell membrane or extracellular structures. Proteoglycans are multifunctional macromolecules that have wide-ranging functions within the body. Not only are they involved in the organization of extracellular functions, they also have cell regulatory functions. These attributes of PGs arise from structural domains that are present on both the core proteins and the GAG chains of this group of macromolecules.