Two different proteoheparan sulfate species are synthesized by bovine corneal endothelial cells.
Cultured bovine corneal endothelial cells were labeled with either [35S]sulfate or a combination of [3H]glucosamine and [35S]methionine. The medium proteoheparan sulfate (HS-PG) and cell-associated HS-PG were isolated and identified as heparan sulfate-containing proteoglycans by the susceptibility of their glycosaminoglycan component to specific enzymatic and chemical degradation. The native medium HS-PG has an apparent Mr of about 300,000 and an Mr of its protein core of 64,000, while the native cell-associated HS-PG had a lower molecular weight (approx. 100,000) and an Mr of its protein core of 33,000. The protein core of both HS-PG types consisted of a single polypeptide chain. After beta-elimination reaction of the native HS-PGs the resulting heparan sulfate side chains of medium HS-PG had an Mr of about 60,000, and those of cell-associated HS-PG an Mr of about 30,000. The different molecular parameters of medium HS-PG and cell-associated HS-PG refer to different functional roles. The medium HS-PG secreted by the endothelial cells is regarded as a metabolic precursor of the Descemet's membrane, while the cell-associated HS-PG might represent a cell membrane-integrated proteoglycan.
Wollensak
J
J
Department of Ophthalmology, University of Berlin, F.R.G.
Schmidt
A
A
Buddecke
E
E
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D011508:Chondroitin Sulfate Proteoglycans / Q000096:biosynthesis* / Q000302:isolation & purification; D004728:Endothelium, Corneal / Q000378:metabolism*; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate / Q000096:biosynthesis* / Q000302:isolation & purification; D008970:Molecular Weight; D011509:Proteoglycans / Q000096:biosynthesis*
D011508:Chondroitin Sulfate Proteoglycans; D006025:Glycosaminoglycans; D019812:Heparan Sulfate Proteoglycans; D006497:Heparan Sulfate; D011509:Proteoglycans