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Biophys J. 2008 Oct;95(8):3861-71. doi: 10.1529/biophysj.108.133744. Epub 2008 Jul 18.

Cholesterol interactions with fluid-phase phospholipids: effect on the lateral organization of the bilayer.

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  • 1Department of Biochemistry and Pharmacy, Abo Akademi University, FIN-20520 Turku, Finland.

Abstract

The lateral organization of lipids and proteins in cell membranes is recognized as an important factor in several cellular processes. Cholesterol is thought to function as a modulator of the lateral segregation of lipids into cholesterol-poor and cholesterol-rich domains. We investigated how the affinity of cholesterol for different phospholipids, as seen in cholesterol partitioning between methyl-beta-cyclodextrin and large unilamellar vesicles, was reflected in the lateral organization of lipids in complex bilayers. We especially wanted to determine how the low-T(m) lipid affected the lateral structure. Partition experiments showed that cholesterol had a higher affinity for N-oleoyl-sphingomyelin (OSM) than for palmitoyl-oleoyl-phosphatidylcholine (POPC) bilayers, but the highest preference was for N-palmitoyl-sphingomyelin (PSM)-containing bilayers. Partial phase diagrams of POPC/PSM/cholesterol and OSM/PSM/cholesterol bilayers at 23 degrees C and 37 degrees C were used to gain insight into the lateral organization of lipids in bilayers. Analysis of phase diagrams revealed that the phospholipid composition of cholesterol-poor and cholesterol-rich domains reflected the affinity that cholesterol exhibited toward bilayers composed of different lipids. Therefore, the determined affinity of cholesterol for different phospholipid bilayers was useful in predicting the cholesterol-induced lateral segregation of lipids in complex bilayers.

PMID:
18641061
[PubMed - indexed for MEDLINE]
PMCID:
PMC2553118
Free PMC Article
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