Remodeling of Ordered Membrane Domains by GPI-Anchored Intestinal Alkaline Phosphatase

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• 作者：Marie-Cé ; cile Giocondi ; F. Besson ; Franç ; oise Besson ; Patrice Dosset ; Pierre-Emmanuel Milhiet
• 刊名：Langmuir
• 出版年：2007
• 出版时间：August 28, 2007
• 年：2007
• 卷：23
• 期：18
• 页码：9358 - 9364
• 全文大小：530K
• 年卷期：v.23,no.18(August 28, 2007)
• ISSN：1520-5827

文摘

Glycosylphosphatidyl-inositol (GPI)-anchored proteins preferentially localize in the most ordered regions of thecell plasma membrane. Acyl and alkyl chain composition of GPI anchors influence the association with the ordereddomains. This suggests that, conversely, changes in the fluid and in the ordered domains lipid composition affect theinteraction of GPI-anchored proteins with membrane microdomains. Validity of this hypothesis was examined byinvestigating the spontaneous insertion of the GPI-anchored intestinal alkaline phophatase (BIAP) into the solid (gel)phase domains of preformed supported membranes made of dioleoylphosphatidylcholine/dipalmitoylphosphatidylcholine(DOPC/DPPC), DOPC/sphingomyelin (DOPC/SM), and palmitoyloleoylphosphatidylcholine/SM (POPC/SM). Atomicforce microscopy (AFM) showed that BIAP inserted in the gel phases of the three mixtures. However, changes inthe lipid composition of membranes had a marked effect on the protein containing bilayer topography. Moreover, BIAPinsertion was associated with a net transfer of phospholipids from the fluid to the gel (DOPC/DPPC) or from the gelto the fluid (POPC/SM) phases. For DOPC/SM bilayers, transfer of lipids was dependent on the homogeneity of thegel SM phase. The data strongly suggest that BIAP interacts with the most ordered lipid species present in the gelphases of phase-separated membranes. They also suggest that GPI-anchored proteins might contribute to the selectionof their own microdomain environment.