Acyl-chain methyl distributions of liquid-ordered and -disordered membranes.

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TitleAcyl-chain methyl distributions of liquid-ordered and -disordered membranes.
Publication TypeJournal Article
Year of Publication2011
AuthorsMihailescu, M, Vaswani, RG, Jardón-Valadez, E, Castro-Román, F, J Freites, A, Worcester, DL, A Chamberlin, R, Tobias, DJ, White, SH
JournalBiophys J
Volume100
Issue6
Pagination1455-62
Date Published2011 Mar 16
ISSN1542-0086
KeywordsCell Membrane, Cholesterol, Lipid Bilayers, Molecular Conformation, Molecular Dynamics Simulation, Phosphatidylcholines
Abstract

A central feature of the lipid raft concept is the formation of cholesterol-rich lipid domains. The introduction of relatively rigid cholesterol molecules into fluid liquid-disordered (L(d)) phospholipid bilayers can produce liquid-ordered (L(o)) mixtures in which the rigidity of cholesterol causes partial ordering of the flexible hydrocarbon acyl chains of the phospholipids. Several lines of evidence support this concept, but direct structural information about L(o) membranes is lacking. Here we present the structure of L(o) membranes formed from cholesterol and dioleoylphosphatidylcholine (DOPC). Specific deuteration of the DOPC acyl-chain methyl groups and neutron diffraction measurements reveal an extraordinary disorder of the acyl chains of neat L(d) DOPC bilayers. The disorder is so great that >20% of the methyl groups are in intimate contact with water in the bilayer interface. The ordering of the DOPC acyl chains by cholesterol leads to retraction of the methyl groups away from the interface. Molecular dynamics simulations based on experimental systems reveal asymmetric transbilayer distributions of the methyl groups associated with each bilayer leaflet.

DOI10.1016/j.bpj.2011.01.035
Alternate JournalBiophys. J.
PubMed ID21402027
PubMed Central IDPMC3059564
Grant ListGM74737 / GM / NIGMS NIH HHS / United States
GM86685 / GM / NIGMS NIH HHS / United States
R01 GM074637 / GM / NIGMS NIH HHS / United States