Involvement of blood-group-B-active trisaccharides in Ca2+-dependent cell-cell adhesion in the Xenopus blastula.
Despite their wide distribution in various organisms, no physiological roles have been proposed for the human blood-group-ABO (ABH)-active trisaccharides. Here we show that monoclonal antibodies against human blood-group-B-active trisaccharides (B-substance) completely block the Ca2+-dependent cell-cell adhesion system of frog (Xenopus laevis) embryonic cells. Synthetic B-substance or B-active glycopeptides also disrupt the Ca2+ -dependent cell-cell adhesion. These results suggest that blood-group-B-active substances play a role in cell-cell adhesion. Blood-group-B-active substances were found as glycoproteins and as glycosphingolipids. In order to identify B-active glycoproteins active in cell-cell adhesion, we purified B-active membrane glycoproteins by two-dimensional electrophoresis and found that they are 45- to 58-kDa proteins with pI(s) ranging from 4.0 to 5.3. They are glycosylphosphatidyl inositol (GPI) anchored. Amino acid sequence analysis showed that the purified B-active GPI-anchored proteins are homologues of soluble Xenopus cortical granule lectins (CGL). The results suggest that the B-active membrane glycoproteins are GPI-anchored forms of the lectin and are directly involved in frog Ca 2+-dependent cell-cell adhesion.
Nomura
K H
KH
Laboratory of Developmental Biology, Department of Biology, Faculty of Science 33, Fukuoka 812, Japan.
Kobayashi
R
R
Hirabayashi
Y
Y
Fujisue-Sakai
M
M
Mizuguchi
S
S
Nomura
K
K
D000017:ABO Blood-Group System / Q000276:immunology*; D000595:Amino Acid Sequence; D000818:Animals; D001755:Blastocyst / Q000276:immunology*; D002118:Calcium / Q000502:physiology*; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology; D002450:Cell Communication / Q000187:drug effects / Q000276:immunology*; D006001:Glycoconjugates / Q000276:immunology / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006801:Humans; D007518:Isoantibodies / Q000494:pharmacology; D008969:Molecular Sequence Data; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D017421:Sequence Analysis; D014312:Trisaccharides / Q000276:immunology* / Q000494:pharmacology; D010738:Type C Phospholipases / Q000494:pharmacology; D014982:Xenopus laevis / Q000196:embryology / Q000276:immunology
D000017:ABO Blood-Group System; D006001:Glycoconjugates; D017261:Glycosylphosphatidylinositols; D007518:Isoantibodies; D014312:Trisaccharides; D010738:Type C Phospholipases; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D002118:Calcium