Characterization of a dermatan sulfate proteoglycan synthesized by murine parietal yolk sac (PYS-2) cells.

A dermatan sulfate proteoglycan has been isolated from a murine parietal yolk sac cell line, which in culture synthesizes basement membrane components. The proteoglycan has a molecular weight of 200,000-300,000 with 10-15 dermatan sulfate chains of Mr = 14,000-16,000. The glycosaminoglycan chains carry sulfate residues predominantly attached to C-4 of the galactosamine unit; less than 10% of the sulfate groups occur as 6-sulfated galactosamine units. About 60% of the uronic acid residues are of the glucuronic configuration, the rest being iduronic acid. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of chondroitinase ABC-treated 125I-labeled proteoglycan reveals two polypeptides with molecular weights of 34,000 and 27,000. Results from papain digestion of the proteoglycan suggest that most of the polysaccharide chains are clustered at a papain-resistant segment of the core protein (Mr = 8,000). This proteoglycan is distinctly different from the large cartilage proteoglycan in the smaller size of its core protein, and its relationship to other small chondroitin and dermatan sulfate proteoglycans and to the chondroitin sulfate proteoglycan recently located in rat tissue basement membranes will be discussed.