Inhibition of ganglioside sialyltransferase activity and stimulation of neutral glycolipid exocytosis by heparin.
Heparin treatment of human teratocarcinoma cells in culture has several manifestations. Accumulation of gangliosides is greatly decreased while the content of cellular neutral glycolipids is relatively unaffected. However, synthesis of neutral glycolipids is increased and large amounts of these glycolipids are exported out of the cells into the medium. In addition, sialyltransferase activity of heparin-treated teratocarcinoma cells is significantly inhibited, accounting for the decreased cellular content of gangliosides. These studies are not intended to infer any physiological role of heparin in the regulation of glycolipid biosynthesis. However, results do show that beta-D-galactoside 2,3-sialyltransferase is a heparin-binding protein and that inhibition of the enzyme activity by heparin is linked to an alteration in the secretion of most neutral glycolipid precursors and sialyltransferase acceptors. These data suggest that in addition to its biosynthetic function, this ganglioside transferase may play a regulatory role in glycolipid secretion.
D001345:Autoradiography; D002460:Cell Line; D002846:Chromatography, Affinity; D004591:Electrophoresis, Polyacrylamide Gel; D005089:Exocytosis / Q000187:drug effects*; D005732:Gangliosides / Q000378:metabolism*; D006017:Glycolipids / Q000096:biosynthesis / Q000378:metabolism*; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D012799:Sialyltransferases / Q000037:antagonists & inhibitors*; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D005732:Gangliosides; D006017:Glycolipids; D006493:Heparin; D012799:Sialyltransferases; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase