Spontaneous insertion and partitioning of alkaline phosphatase into model lipid rafts

AUTOR(ES)

Milhiet, Pierre-Emmanuel

FONTE

Oxford University Press

RESUMO

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.

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