Characterization of a glycophospholipid intermediate in the biosynthesis of glyco-phosphatidylinositol anchors accumulating in the Thy-1-negative lymphoma line SIA-b

• Published in: The Journal of biological chemistry Vol. 266; no. 31; pp. 21051 - 21059
• Main Authors: Puoti, A, Desponds, C, Fankhauser, C, Conzelmann, A
• Format: Journal Article
• Language: English
• Published: 01.01.1991
• Subjects: cell membranes; glycophosphatidylinositol
• ISSN: 0021-9258

Several mammalian mutant cell lines are deficient in the biosynthesis of glyco-phosphatidylinositol anchors for membrane proteins. When metabolically labeled with ( super(3)H)myo-inositol or ( super(3)H)mannose, two out of five mutant lines (SIA-b and EL4-f) accumulated abnormal lipids which remained undetectable in the corresponding parental cell lines. The most abundant glycolipid of SIA-b cells (named lipid X) was isolated and partially characterized using hydrofluoric acid, nitrous acid deamination, acetolysis, and exoglycosidase treatments alone or in combination. The partial structure for the carbohydrate moiety of lipid X is Man alpha -(X arrow right )Man alpha -GlcN-inositol, X being a charged, HF-sensitive substituent (possibly phosphoethanolamine). Lipid X is largely resistant to phosphatidylinositol-specific phospholipase C treatment but can be rendered sensitive to the enzyme by treatment with methanolic NH sub(3), which suggests the presence of an acyl chain on the inositol moiety.