Synthesis of lactosaminoglycan-containing glycoproteins by vascular endothelial cells.
Human vascular endothelial cells synthesize lactosaminoglycan-type glycoproteins which are found both associated with cells and secreted into the culture medium. Pronase-derived glycopeptides prepared from [3H]glucosamine-labeled glycoproteins were found to contain about 10% of the labeled products as a large size (Mr greater than 5000) 3H-labeled glycopeptide. Digestion of these 3H-labeled glycopeptides with endo-beta-galactosidase resulted in the release of smaller size saccharides, which were characterized as having the structure sialic acid----Gal----GlcNAc----Gal. Treatment of [3H]glucosamine-labeled cells with melittin caused 3H-labeled glycoconjugates to be released from the cells. Separation of released glycoproteins from proteoglycans by DEAE-cellulose chromatography indicated that melittin had released 25% of the total 3H-labeled glycoproteins from the cell and 3% of the 3H-labeled proteoglycans. The 3H-labeled glycoproteins were digested with Pronase and the resulting 3H-labeled glycopeptides were fractionated on Sephadex G-50. The large size fraction (Mr greater than 5000) now comprised about 30% of these released 3H-labeled glycopeptides. These high molecular weight 3H-labeled glycopeptides were degraded with endo-beta-galactosidase but not with testicular hyaluronidase. Analysis of the released 3H-labeled glycoproteins indicated a preferential release of glycoproteins of 70-90 kDa enriched in lactosaminoglycan-type oligosaccharides.
D000606:Amino Sugars / Q000096:biosynthesis* / Q000302:isolation & purification; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004727:Endothelium / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006023:Glycoproteins / Q000096:biosynthesis* / Q000302:isolation & purification; D006801:Humans; D008555:Melitten / Q000494:pharmacology; D011134:Polysaccharides / Q000096:biosynthesis* / Q000302:isolation & purification; D011247:Pregnancy; D014471:Umbilical Veins / Q000378:metabolism*
D000606:Amino Sugars; D006023:Glycoproteins; D011134:Polysaccharides; C039448:lactosaminoglycan; D008555:Melitten