title: Temperature-dependent localization of GPI-anchored intestinal alkaline phosphatase in model rafts.
abstract: In plasma membranes, most of glycosylphosphatidylinositol (GPI)-anchored proteins would be associated with rafts, a category of ordered microdomains enriched in sphingolipids and cholesterol (Ch). They would be also concentrated in the detergent resistant membranes (DRMs), a plasma membrane fraction extracted at low temperature. Preferential localization of GPI-anchored proteins in these membrane domains is essentially governed by their high lipid order, as compared to their environment. Changes in the temperature are expected to modify the membrane lipid order, suggesting that they could affect the distribution of GPI-anchored proteins between membrane domains. Validity of this hypothesis was examined by investigating the temperature-dependent localization of the GPI-anchored bovine intestinal alkaline phophatase (BIAP) into model raft made of palmitoyloleoylphosphatidylcholine/sphingomyelin/cholesterol (POPC/SM/Chl) supported membranes. Atomic force microscopy (AFM) shows that the inserted BIAP is localized in the SM/Chl enriched ordered domains at low temperature. Above 30 degrees C, BIAP redistributes and is present in both the 'fluid' POPC enriched and the ordered SM/Chl domains. These data strongly suggest that in cells the composition of plasma membrane domains at low temperature differs from that at physiological temperature.
authors: Institut National de la Santé et de la Recherche Médicale, Unité 554, Montpellier, France.
authors: Marie-Cécile
authors: MC
authors: Giocondi
authors: Françoise
authors: F
authors: Besson
authors: Patrice
authors: P
authors: Dosset
authors: Pierre-Emmanuel
authors: PE
authors: Milhiet
authors: Christian
authors: C
authors: Le Grimellec
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D017261:Glycosylphosphatidylinositols / Q000737:chemistry / Q000378:metabolism*; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism*; D008560:Membrane Fluidity / Q000502:physiology; D021962:Membrane Microdomains / Q000378:metabolism* / Q000648:ultrastructure*; D018625:Microscopy, Atomic Force; D008954:Models, Biological; D013696:Temperature; D014018:Tissue Distribution
chemical_list: D017261:Glycosylphosphatidylinositols; D007527:Isoenzymes; C415670:Alpi protein, rat; D000469:Alkaline Phosphatase