Remodeling of ordered membrane domains by GPI-anchored intestinal alkaline phosphatase.
Glycosylphosphatidyl-inositol (GPI)-anchored proteins preferentially localize in the most ordered regions of the cell plasma membrane. Acyl and alkyl chain composition of GPI anchors influence the association with the ordered domains. This suggests that, conversely, changes in the fluid and in the ordered domains lipid composition affect the interaction of GPI-anchored proteins with membrane microdomains. Validity of this hypothesis was examined by investigating 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). Atomic force microscopy (AFM) showed that BIAP inserted in the gel phases of the three mixtures. However, changes in the lipid composition of membranes had a marked effect on the protein containing bilayer topography. Moreover, BIAP insertion was associated with a net transfer of phospholipids from the fluid to the gel (DOPC/DPPC) or from the gel to the fluid (POPC/SM) phases. For DOPC/SM bilayers, transfer of lipids was dependent on the homogeneity of the gel SM phase. The data strongly suggest that BIAP interacts with the most ordered lipid species present in the gel phases of phase-separated membranes. They also suggest that GPI-anchored proteins might contribute to the selection of their own microdomain environment.
Institut National de la Santé et de la Recherche Médicale, Unité 554, Montpellier, France.
Marie-Cécile
MC
Giocondi
Françoise
F
Besson
Patrice
P
Dosset
Pierre-Emmanuel
PE
Milhiet
Christian
C
Le Grimellec
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000469:Alkaline Phosphatase / Q000737:chemistry* / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000737:chemistry* / Q000378:metabolism*; D005782:Gels / Q000737:chemistry; D017261:Glycosylphosphatidylinositols / Q000737:chemistry / Q000378:metabolism*; D007422:Intestines / Q000201:enzymology*; D008051:Lipid Bilayers; D018625:Microscopy, Atomic Force; D010713:Phosphatidylcholines / Q000737:chemistry; D013109:Sphingomyelins / Q000737:chemistry
D005782:Gels; D017261:Glycosylphosphatidylinositols; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D013109:Sphingomyelins; D015060:1,2-Dipalmitoylphosphatidylcholine; D000469:Alkaline Phosphatase; C017251:1,2-oleoylphosphatidylcholine