Structures of the O-glycans on P-selectin glycoprotein ligand-1 from HL-60 cells.
P-selectin glycoprotein ligand-1 (PSGL-1) is a disulfide-bonded homodimeric mucin-like glycoprotein on leukocytes that interacts with both P- and E-selectin. In this report we describe the structures of the Ser/Thr-linked O-glycans of PSGL-1 synthesized by HL-60 cells metabolically radiolabeled with 3H-sugar precursors. In control studies, the O-glycans on CD43 (leukosialin), a mucin-like glycoprotein also expressed by HL-60 cells, were analyzed and compared to those of PSGL-1. O-Glycans were released from Ser/Thr residues by mild base/borohydride treatment of purified glycoproteins, and glycan structures were determined by a combination of techniques. In contrast to expectations, PSGL-1 is not heavily fucosylated; a majority of the O-glycans are disialylated or neutral forms of the core-2 tetrasaccharide Galbeta1-->4GlcNAcbeta1-->6(Galbeta1-->3)GalNAcOH++ +. A minority of the O-glycans are alpha-1,3-fucosylated that occur as two major species containing the sialyl Lewis x antigen; one species is a disialylated, monofucosylated glycan, and the other is a monosialylated, trifucosylated glycan having a polylactosamine backbone. CD43 lacks the fucosylated glycans found on PSGL-1 and is enriched for the nonfucosylated, disialylated core-2 hexasaccharide. These results demonstrate that PSGL-1 contains unique fucosylated O-glycans that are predicted to be critical for high affinity interactions between PSGL-1 and selectins.
Wilkins
P P
PP
Department of Biochemistry, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190, USA.
McEver
R P
RP
Cummings
R D
RD
D015703:Antigens, CD; D002240:Carbohydrate Sequence; D002460:Cell Line; D006026:Glycoside Hydrolases; D006031:Glycosylation; D018922:HL-60 Cells / Q000737:chemistry*; D006801:Humans; D051917:Leukosialin; D008024:Ligands; D008562:Membrane Glycoproteins / Q000737:chemistry*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000737:chemistry; D019007:P-Selectin / Q000302:isolation & purification / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry*; D012795:Sialoglycoproteins / Q000737:chemistry / Q000302:isolation & purification; D000080506:Sialyl Lewis X Antigen
D015703:Antigens, CD; D051917:Leukosialin; D008024:Ligands; D008562:Membrane Glycoproteins; D009844:Oligosaccharides; D019007:P-Selectin; C084882:P-selectin ligand protein; D011134:Polysaccharides; C465014:SPN protein, human; D012795:Sialoglycoproteins; D000080506:Sialyl Lewis X Antigen; D006026:Glycoside Hydrolases