Structure of Oriented Lipid Bilayers

Levine, Y.K.; Wilkins, M. H. F.

doi:10.1038/newbio230069a0

Cited by 330 publications

(200 citation statements)

References 19 publications

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“…43 We will write the interaction energy between neighboring all-trans phospholipid chains in the form wtt = wtto(n -2) (2. 26) where n -2 is an approximate representation of the actual overlapping length of neighboring n-carbon chains.24 A similar expression Wkk = Wkko(n -2) (2. 27) should adequately represent the interaction between dovetailed kinky chains when only a few gauche rotations are present.…”

Section: Model For Pure Lamellar Phospholipid Bilayer Phase Transitionsmentioning

confidence: 98%

Semiempirical models for biomembrane phase transitions and phase separations

McCammon¹,

Deutch²

1975

J. Am. Chem. Soc.

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Experimental studies are reviewed to construct a model for the hydrocarbon chain disordering in "fluid" phospholipid bilayers. Together with approximate expressions for the interactions between neighboring molecules, this information is used to construct a simple statistical thermodynamic theory of the chain "melting" based on the Bragg-Williams approximation. Two unknown parameters in the theory, the interaction between neighboring chains in the "fluid" state and the change in head group interaction associated with the chain "melting", are determined for particular classes of phospholipids by reference to experimental data. The theory is applied to predict the "melting" temperatures of single-component bilayers and the phase diagrams of two-component bilayers. Possible extensions of this type of theory to rationalize other phenomena observed in biological membranes are discussed.

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Section: Model For Pure Lamellar Phospholipid Bilayer Phase Transitionsmentioning

confidence: 98%

Semiempirical models for biomembrane phase transitions and phase separations

McCammon¹,

Deutch²

1975

J. Am. Chem. Soc.

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“…A crucial step in cholesterol homeostasis is action of a cholesterol-sensing machinery at the endoplasmic reticulum (5). Within the cell, the cholesterol distribution between membranes is also actively regulated, resulting in a concentration gradient along the secretory pathway, with low concentrations of cholesterol in the ER 1 and high concentrations in the plasma membrane (6,7). The Golgi apparatus contains intermediate levels of cholesterol (7), and there are indications of a cholesterol gradient even within the Golgi complex (8 -11).…”

mentioning

confidence: 99%

“…By interacting with the acyl-chain of other (phospho)lipids, cholesterol increases lipid packing in the membranes, thereby causing thickening of the membrane. Increased packing of the membrane affects the fluidity of the membrane and makes it less permeable for the transbilayer passage of small water-soluble molecules like glucose (1)(2)(3). Total cellular cholesterol levels are determined by de novo synthesis in the endoplasmic reticulum, by the uptake of extracellular cholesterol from, e.g.…”

mentioning

confidence: 99%

Intra-Golgi Protein Transport Depends on a Cholesterol Balance in the Lipid Membrane

Stüven

Porat

Shimron

et al. 2003

Journal of Biological Chemistry

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Transport of proteins between intracellular membrane compartments is mediated by a protein machinery that regulates the budding and fusion processes of individual transport steps. Although the core proteins of both processes are defined at great detail, much less is known about the involvement of lipids. Here we report that changing the cellular balance of cholesterol resulted in changes of the morphology of the Golgi apparatus, accompanied by an inhibition of protein transport. By using a well characterized cell-free intra-Golgi transport assay, these observations were further investigated, and it was found that the transport reaction is sensitive to small changes in the cholesterol content of Golgi membranes. Addition as well as removal of cholesterol (10 ؎ 6%) to Golgi membranes by use of methyl-␤-cyclodextrin specifically inhibited the intra-Golgi transport assay. Transport inhibition occurred at the fusion step. Modulation of the cholesterol content changed the lipid raft partitioning of phosphatidylcholine and heterotrimeric G proteins, but not of other (non) lipid raft proteins and lipids. We suggest that the cholesterol balance in Golgi membranes plays an essential role in intra-Golgi protein transport and needs to be carefully regulated to maintain the structural and functional organization of the Golgi apparatus.

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“…The second term is about 1% of the first term, because for energies below the absorption edge f λ ″ (~0.5) is about 1/10 of f′ (Figure 1). Therefore we have the approximate relation (2) We now plot |F λ | against -f′ λ /f n (or |f′ λ |/f n ) for each peak (Figure 4). The data for every peak appear to satisfy a linear relation (i.e., a straight line).…”

Section: Iif Mad Analysismentioning

confidence: 99%

Chain Packing in the Inverted Hexagonal Phase of Phospholipids: A Study by X-ray Anomalous Diffraction on Bromine-labeled Chains

et al. 2006

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Although lipid phases are routinely studied by X-ray diffraction, their unit cell structures have rarely been constructed from the diffraction data except for the lamellar phases. This is due to the wellknown phase problem of X-ray diffraction. Here we successfully applied the multiwavelength anomalous dispersion (MAD) method to solve the phase problem for an inverted hexagonal phase of a phospholipid with brominated chains. Although the principle of the MAD method for all systems is the same, we found that for lipid structures it is necessary to use a procedure of analysis significantly different from that used for protein crystals. The inverted hexagonal phase has been used to study the chain packing in a hydrophobic interstice where three monolayers meet. Hydrophobic interstices are of great interest, because they occur in the intermediate states of membrane fusion. It is generally believed that chain packing in such a region is energy costly. Consequently it has been speculated that the inverted lipid tube is likely to deviate from a circular shape, and the chain density distribution might be non-uniform. The bromine distribution obtained from the MAD analysis provides the information for the chain packing in the hexagonal unit cell. The intensity of the bromine distribution is undulated around the unit cell. The analysis shows that the lipid chains pack the hexagonal unit cell at constant volume per chain, with no detectable effect from a high-energy interstitial region.

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Structure of Oriented Lipid Bilayers

Cited by 330 publications

References 19 publications

Semiempirical models for biomembrane phase transitions and phase separations

Semiempirical models for biomembrane phase transitions and phase separations

Intra-Golgi Protein Transport Depends on a Cholesterol Balance in the Lipid Membrane

Chain Packing in the Inverted Hexagonal Phase of Phospholipids: A Study by X-ray Anomalous Diffraction on Bromine-labeled Chains

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