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BA Sullenbarger, MS Petitt, P Chong, MW Long and MS Wicha
Department of Internal Medicine, University of Michigan, Simpson Memorial
Institute, Ann Arbor 48109-0724, USA.
Hemonectin (HN) is a bone marrow (BM) protein that promotes specific
attachment of immature granulocytes and their precursors within the BM. We
report that HN is a glycoprotein containing both mannose and galactose
residues, and provide evidence that these carbohydrates mediate
granulocytic cell adhesion to HN. Carbohydrate structure was determined by
digoxigenin-conjugated lectin binding to HN and indicated the presence of
mannose, galactose, sialic acid, and the absence of fucose-linked
oligosaccharides. The role of carbohydrates in mediating cell adhesion was
examined by chemical and enzymatic deglycosylation. Deglycosylation of HN
with trifluoromethanesulfonic acid, which cleaves N- and O-linked
oligosaccharides, inhibits 66% of cell attachment to HN, and results in an
apparent decrease in molecular weight from 60 to 50 kD. Enzymatic
deglycosylation with endo-B-N-acetylglucosaminidase H, which hydrolyzes
specific N-linked mannose residues, inhibits 30% of cell adhesion to HN.
Finally, the role of these specific sugars in hemonectin-mediated cell
adhesion was confirmed with neoglycoprotein blocking. Preincubation of BM
cells with mannosyl- and galactosyl-BSA probes produces a dose-dependent
inhibition of cell attachment to HN, whereas fucosyl-BSA does not inhibit
cell adhesion to HN. These results show that mannose and galactose
partially mediate adhesion of BM granulocytes to HN.
This article has been cited by other articles:
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| Copyright © 1995 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
