Study of O-glycan sialylation in C6 cultured glioma cells: evidence for post-translational regulation of a beta-galactoside alpha 2,3 sialyltransferase activity by N-glycosylation.
We have studied the Gal beta 1-3GalNAc-R alpha 2,3 sialyltransferase from C6 glioma cells transferring Neu5Ac from CMP-Neu5Ac onto O-glycans of glycoproteins. Using synchronized C6 glioma cells, we showed that the alpha 2,3 sialyltransferase activity was inhibited by tunicamycin to a greater extend than DNA and protein biosynthesis suggesting inhibition of N-glycosylation of this enzyme. Additional demonstration of N-glycosylation of the alpha 2,3 sialytransferase was provided through ConA-Sepharose binding. Treatment of partially purified alpha 2,3 sialytransferase by peptide-N-glycosidase F showed a significative inhibition demonstrating that N-glycan moiety is required for complete activity of the C6 glioma cell alpha 2,3 sialyltransferase.
Broquet
P
P
Laboratoire de Biochimie Générale et Médicale, INSERM-CNRS U.189 Faculté de Médecine Lyon-Sud, Oullins, France.
George
P
P
Geoffroy
J
J
Reboul
P
P
Louisot
P
P
D000818:Animals; D002460:Cell Line; D002846:Chromatography, Affinity; D003208:Concanavalin A; D004261:DNA Replication / Q000187:drug effects; D005910:Glioma; D006023:Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D006031:Glycosylation; D007700:Kinetics; D011499:Protein Processing, Post-Translational; D051381:Rats; D012799:Sialyltransferases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D014415:Tunicamycin / Q000494:pharmacology; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase
D006023:Glycoproteins; D003208:Concanavalin A; D014415:Tunicamycin; D012799:Sialyltransferases; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase