Evidence for a glycolipid anchor of gp64, a putative cell-cell adhesion protein of Polysphondylium pallidum.
The membrane-bound glycoprotein (gp64) of the cellular slime mold Polysphondylium pallidum, is a putative cell-cell adhesion protein identified by adhesion-blocking antibody fragments. Since gp64 can be purified in a few days and in substantial yields, it is a good candidate for clarifying the structure of a cell-cell adhesion protein. This study reveals that gp64 possesses a glycolipid anchor which is sensitive to deamination but resistant to phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis. Although the anchor resistance to phosphatidylinositol-specific phospholipase C can be ascribed to the presence of an additional acyl chain on the inositol ring in the glycosyl phosphatidylinositol anchors, this was not the case. After a mild-base treatment that released an additional acyl chain on the inositol ring, only a trace amount of fatty acid was detected but, after strong acid hydrolysis, we detected both amide-linked fatty acids and a long-chain base. The long-chain base was further analysed by gas-chromatography/mass spectrometry and was found to be phytosphingosine. Both fatty acids and myo-inositol were also analysed by gas-chromatography/mass spectrometry. These data suggest that gp64 possesses a glycolipid anchor which contains ceramide and myo-inositol.
Saito
T
T
Department of Biology, Faculty of Science, Hokkaido University, Sapporo, Japan.
Ochiai
H
H
D001413:Bacillus thuringiensis / Q000201:enzymology; D015815:Cell Adhesion Molecules / Q000032:analysis*; D002518:Ceramides / Q000032:analysis; D002855:Chromatography, Thin Layer; D005656:Fungal Proteins / Q000032:analysis*; D017261:Glycosylphosphatidylinositols / Q000032:analysis*; D013058:Mass Spectrometry; D009235:Myxomycetes / Q000737:chemistry*; D009609:Nitrous Oxide / Q000494:pharmacology; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000494:pharmacology
D015815:Cell Adhesion Molecules; D002518:Ceramides; D005656:Fungal Proteins; D017261:Glycosylphosphatidylinositols; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D009609:Nitrous Oxide