Biosynthesis and interactions of small chondroitin/dermatan sulphate proteoglycans.

This review pays special attention to the structure and functions of two chondroitin/dermatan sulphate proteoglycans which are members of the family of small leucine-rich proteoglycans of the extracellular matrix. Novel data are presented indicating the importance of the core protein for the determination of the extent of glycosaminoglycan modification. Decorin as well as biglycan are able to associate specifically with type I collagen fibrils and to interact with several other components of the extracellular matrix. Recombinant fragments of both proteoglycans inhibit collagen fibrillogenesis. Evidence is presented for the functional diversity of decorin core protein. Considering the proposal of a glycosaminoglycan-glycosaminoglycan interaction, data are presented indicating that exclusively glycosaminoglycan chains containing a peptide moiety of more than two amino acids are able to interact with native decorin, suggesting that protein-protein or protein-glycosaminoglycan interactions are of importance in this respect, too. The interactions of decorin with growth factors are discussed, and it is shown that complexes of transforming growth factor-beta and decorin are still able to exhibit some but not all the specific effects of the uncomplexed cytokine.