Different galactosaminoglycan composition of small proteoglycans from osteosarcoma cells

The expression of the core proteins and the co-polymeric structureof the glycosaminoglycan chains of three different small proteoglycans(biglycan, decorin, proteoglycan-100) have been examined inthe human osteosarcoma cell line MG-63. The three proteoglycans,which are carrying either one or two chondroitin/dermatan sulphatechains, were synthesized in a similar molar ratio, as determinedby ³⁵S]methionine as well as by ³⁵S]sulphate incorporation.After sulphate ester formation, they were secreted into theculture medium with similar kinetics. Immune staining with monospecificantibodies revealed that at least biglycan and proteoglycan-100were present in all individual cells. However, in contrast tothese similarities, the glycosaminoglycan moiety of proteoglycan-100was composed exclusively of chondroitin 4- and 6-sulphate repeatingunits, whereas biglycan and decorin contained hybrid polymersof chondroitin and dermatan sulphate with