@entity26720 ( XXXX ) as ligand for @entity19 P-selectin.

@entity852 @entity3167 @entity19 @entity52140 @entity1735 @entity14879 @entity26720 @entity4496
@entity26720 (HSA)/ @entity26720 is a cell surface molecule expressed by many cell types in the @entity19 . The molecule has an unusual structure because of its small protein core and extensive glycosylation. In order to study the functional role of the HSA-associated glycoconjugates we have isolated different forms of HSA. Using lectin analysis we provide evidence for extensive heterogeneity in @entity1735 composition and @entity3167 linkage. Several HSA forms were recognized by @entity19 P-selectin-IgG but not E-selectin-IgG in ELISA. As expected, P-selectin-IgG also bound to L2/ @entity52140 -positive neural glycoproteins (L2-glycoproteins) and @entity4496 but not to gangliosides and other control glycoproteins. The binding of P-selectin-IgG to L2-glycoproteins and HSA required bivalent cations. The reactivity to HSA was sensitive to sialidase treatment whereas the binding to L2-glycoproteins was not. Studies with alpha 2-6 sialytransferase indicated that alpha 2-6 linked @entity3167 was not involved in the P-selectin binding to HSA. Surprisingly, an L2/ @entity52140 specific antibody was found to cross-react with some HSA glycoforms and its binding correlated with P-selectin-IgG reactivity. L2/ @entity52140 -positive or L2/ @entity52140 -negative HSA glycoforms were also analyzed after coating to @entity852 beads. Only the L2/ @entity52140 -positive HSA coated beads were reactive with P-selectin-IgG and could bind to activated @entity14879 endothelioma cells expressing P-selectin whereas the L2/ @entity52140 -negative HSA beads did not. It is suggested that in its L2/ @entity52140 modified form the HSA molecule on leukocytes could represent a ligand for P-selectin on endothelial cells or platelets.
