title: Spontaneous insertion and partitioning of alkaline phosphatase into model lipid rafts.
abstract: Several cell surface eukaryotic proteins have a glycosylphosphatidylinositol (GPI) modification at the C-terminal end that serves as an anchor to the plasma membrane and could be responsible for the presence of GPI proteins in rafts, a type of functionally important membrane microdomain enriched in sphingolipids and cholesterol. In order to understand better how GPI proteins partition into rafts, the insertion of the GPI-anchored alkaline phosphatase (AP) was studied in real-time using atomic force microscopy. Supported phospholipid bilayers made of a mixture of sphingomyelin-dioleoylphosphatidylcholine containing cholesterol (Chl+) or not (Chl-) were used to mimic the fluid-ordered lipid phase separation in biological membranes. Spontaneous insertion of AP through its GPI anchor was observed inside both Chl+ and Chl- lipid ordered domains, but AP insertion was markedly increased by the presence of cholesterol.
authors.affiliation: Centre de Biochimie Structurale, CNRS UMR 5048 Université Montpellier I, INSERM UMR554, 29 rue de Navacelles, F-34090 Montpellier cedex, France.
authors.forename: Pierre-Emmanuel
authors.initials: PE
authors.lastname: Milhiet
authors.forename: Marie-Cécile
authors.initials: MC
authors.lastname: Giocondi
authors.forename: Omid
authors.initials: O
authors.lastname: Baghdadi
authors.forename: Frédéric
authors.initials: F
authors.lastname: Ronzon
authors.forename: Bernard
authors.initials: B
authors.lastname: Roux
authors.forename: Christian
authors.initials: C
authors.lastname: Le Grimellec
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D021962:Membrane Microdomains / Q000201:enzymology*; D018625:Microscopy, Atomic Force; D010713:Phosphatidylcholines / Q000378:metabolism; D013107:Sphingolipids / Q000378:metabolism
chemical_list: D010713:Phosphatidylcholines; D013107:Sphingolipids; D000469:Alkaline Phosphatase; C017251:1,2-oleoylphosphatidylcholine