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Title

Distinct interactions among GPI-anchored, transmembrane and membrane associated intracellular proteins, and sphingolipids in lymphocyte and endothelial cell plasma membranes

Authors
Briol, A.
Published in Biochimica et Biophysica Acta. 1997, vol. 1328, no. 2, p. 227-236
Abstract Glycosylphosphatidylinositol (GPI)-anchored glycoproteins are enriched in sphingolipid-rich plasma membrane domains, which are often isolated as low-density membrane complexes. This association is believed to arise from the interactions between the GPI-acyl chains and sphingolipids, but is not fully understood. In this study, we compared the physical properties of GPI-anchored glycoproteins from a non-polarized (murine T-lymphocyte) and a polarized (human endothelial) cell by equilibrium density gradient centrifugation after extraction by detergents under identical conditions. Unlike those on epithelial cells, the GPI-anchored proteins of lymphocytes (Thy-1 and the heat stable antigen CD24) were enriched in the floating fractions after extraction over a wide range of octylglucoside concentrations. In contrast, the floatability of endothelial GPI-anchored CD59 was markedly diminished, not only by octylglucoside, but also by increasing concentrations of Triton X-100. Distribution of cholera toxin binding ganglioside GM1 in the sucrose gradient fractions closely followed that of the GPI-anchored proteins in both lymphocytes and endothelial cells under most extraction conditions. Analysis of the intracellular acylated molecules revealed that a significant amount of p56(lck) was always associated with the floating GPI-rich fractions of lymphocytes when extracted by Triton X-100 or octylglucoside at 4 degrees C, while the behaviour of endothelial cell caveolin was comparable to that of CD59. The transmembrane glycoproteins CD45 in lymphocytes and MHC class I antigen in endothelial cells interacted weakly with GPI domains, whereas endothelial CD44 and lymphocyte CD26 displayed a strong association. These results show that: (1) the physical properties of different GPI-anchored proteins may vary significantly; and (2) transmembrane and acylated intracellular proteins could be associated with GPI domains to a variable extent. These differences probably reflect cell type-specific interactions of GPI anchors with the sphingolipid framework of plasma membranes, as well as extracellular interactions of GPI-anchored glycoproteins with neighbouring cell surface molecules.
Keywords AnimalsCell Membrane/ chemistryCell PolarityCentrifugation, Density GradientEndothelium, Vascular/ chemistry/cytologyG(M1) Ganglioside/analysisGlycosylphosphatidylinositols/ analysisHumansLymphocytes/ chemistry/cytologyMembrane Proteins/ analysisRatsSphingolipids/ analysisSubcellular Fractions/chemistry
Identifiers
PMID: 9315619
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ILANGUMARAN, Subburaj, BRIOL, A., HOESSLI, Daniel. Distinct interactions among GPI-anchored, transmembrane and membrane associated intracellular proteins, and sphingolipids in lymphocyte and endothelial cell plasma membranes. In: Biochimica et Biophysica Acta, 1997, vol. 1328, n° 2, p. 227-236. https://archive-ouverte.unige.ch/unige:11322

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Deposited on : 2010-08-27

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