Occurrence of a novel fucose-containing pentaglycosylceramide with blood-group-B active determinant in Xenopus blastula cells: Its possible involvement in cell-cell adhesion

For understanding of the biological function of glycoconjugates during embryogenesis and morphogenesis, Xenopus laevis is considered a very useful animal model. We have found that blood-group-active molecules characteristically were distributed in the cell-cell contact region of Xenopus blastula cells. The chemical nature of blood-group-active glycoconjugates, including glycosphingolipids, is little known. T.l.c.-immunostaining using anti-blood-group-antigen antibodies showed that many species of blood group-B-active glycosphingolipids existed in the neutral glycosphingolipid fraction extracted from Xenopus laevis eggs. Among the B-active glycosphingolipids detected, two major components with the fastest mobility on a t.l.c. plate, tentatively termed XN-1 and XN-2, were isolated, and their chemical structures were characterized by gas chromatography-mass spectrometry, immunological analysis, fast-atom-bombardment mass spectrometry and ¹H-n.m.r, spectroscopy. Both XN-1 and XN-2 had an identical pentaoligosaccharide structure, but differed in their ceramide moiety. The chemical structure is: Galα1-3 Galβ1-3Galβ1-4Glcβ1-1'Cer Fucα1-2 This is a novel type of pentaglycosylceramide with blood-group B activity, in that it lacks N-acetylhexosamine in its core carbohydrate structure, In this paper, a possible involvement of the blood-group antigen in the cell-adhesion process of Xenopus embryonic cells is discussed.