Functional Aspects of Proteoglycan Domain Structure

Abstract

Proteoglycans, a class of extracellular macromolecules characteristically consisting of a protein core substituted with one or several glycosaminoglycan chains, have a profound influence on the physical properties of the extracellular matrix and the pericellular space. Many proteoglycans have a multidomain structure where distinct biological properties can be assigned to particular, often well conserved portions of the protein core. In the present chapter we review the functional aspects of proteoglycan domain structure using the large aggregating class of interstitial matrix proteoglycans as an example. These molecules are abundant in many types of extracellular matrix, but most pronouncedly so in cartilage. There they do by formation of large aggregates with hyaluronate fill the space between collagen fibers and make the tissue resilient to pressure (for review see Heinegård and Paulsson, 1984). Interstitial matrix does in addition contain two or more distinct populations of small proteoglycans. At least certain members of the class of small proteoglycans have affinity for collagen fibrils and are thought to regulate collagen fibril formation (Scott and Orford, 1981? Vogel et al, 1984).