Identification of a tetrasialylated monofucosylated tetraantennary N-linked carbohydrate chain in human platelet glycocalicin.
Glycocalicin (140 kDa), the main constituent of the glycoprotein Ib alpha-chain (150 kDa) of the human platelet membrane, contains 4 putative N-glycosylation sites. For the structural analysis of the N-glycosidic carbohydrate chains of glycocalicin, the glycoprotein has been subjected to the hydrazinolysis procedure. The acidic carbohydrate chains obtained were fractionated by ion-exchange chromatography on DEAE-Sephadex A-25, and subsequently analyzed by sugar analysis, anion-exchange chromatography on Mono Q HR 5/5 and 500 MHz 1H-NMR spectroscopy. A novel tetrasialylated monofucosylated tetraantennary chain was identified in the glycoprotein. It could also be deduced that in all structures the alpha 2----6-linked NeuAc is attached exclusively at the Gal beta 1----2Man alpha 1----3 antenna, whereas the other antennae can be terminated with alpha 2----3-linked NeuAc. As minor constituents sialylated N-linked carbohydrate chains with a terminal Fuc alpha 1----2Gal beta 1----sequence were detected.
Korrel
S A
SA
Department of Bio-Organic Chemistry, Utrecht University, The Netherlands.
Clemetson
K J
KJ
van Halbeek
H
H
Kamerling
J P
JP
Sixma
J J
JJ
Vliegenthart
J F
JF
D000606:Amino Sugars / Q000032:analysis; D001792:Blood Platelets / Q000032:analysis*; D002236:Carbohydrate Conformation; D002241:Carbohydrates / Q000032:analysis*; D002462:Cell Membrane / Q000032:analysis; D002852:Chromatography, Ion Exchange; D005643:Fucose / Q000032:analysis*; D006031:Glycosylation; D006801:Humans; D006834:Hydrazines; D009682:Magnetic Resonance Spectroscopy; D019158:N-Acetylneuraminic Acid; D019038:Platelet Glycoprotein GPIb-IX Complex; D010980:Platelet Membrane Glycoproteins / Q000032:analysis*; D012794:Sialic Acids / Q000032:analysis*
D000606:Amino Sugars; D002241:Carbohydrates; D006834:Hydrazines; D019038:Platelet Glycoprotein GPIb-IX Complex; D010980:Platelet Membrane Glycoproteins; D012794:Sialic Acids; C023592:glycocalicin; C029424:hydrazine; D005643:Fucose; C000458:N-acetyllactosamine; D019158:N-Acetylneuraminic Acid