title: A novel class of cell surface glycolipids of mammalian cells. Free glycosyl phosphatidylinositols.
abstract: Glycosyl phosphatidylinositol (GPI) lipids function as anchors of membrane proteins, and free GPI units serve as intermediates along the path of GPI-anchor biosynthesis. By using in vivo cell surface biotinylation, we show that free GPIs: 1) can exit the rough endoplasmic reticulum and are present on the surface of a murine EL-4 T-lymphoma and a human carcinoma cell (HeLa), 2) arrive at the cell surface in a time and temperature-dependent fashion, and 3) are built on a base-labile glycerol backbone, unlike GPI anchors of surface proteins of the same cells. The free GPIs described in this study may serve as a source of hormone-sensitive phosphoinositol glycans. The absence of free GPIs from the cell surface may also account for the growth advantage of blood cells in paroxysmal nocturnal hemoglobinuria.
authors.affiliation: Institute of Pathology and Cell Biology Program, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: N
authors.initials: N
authors.lastname: Singh
authors.forename: L N
authors.initials: LN
authors.lastname: Liang
authors.forename: M L
authors.initials: ML
authors.lastname: Tykocinski
authors.forename: A M
authors.initials: AM
authors.lastname: Tartakoff
mesh_terms: D000818:Animals; D001692:Biological Transport; D001710:Biotin / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D018870:Endoplasmic Reticulum, Rough / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D014407:Tumor Cells, Cultured
chemical_list: D017261:Glycosylphosphatidylinositols; D001710:Biotin