Bilayer Structure in Membranes

Wilkins, M. H. F.; Blaurock, A.E.; Engelman, Donald M.

doi:10.1038/newbio230072a0

Cited by 263 publications

(134 citation statements)

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“…We directly test the effect of both cholesterol and resident membrane proteins on the thickness of cell membranes by using solution x-ray scattering (SXS) on membrane fractions purified from rat hepatocytes and Escherichia coli. SXS has been successfully implemented in directly measuring the average bilayer thickness of liposomes and the plasma membrane of Mycoplasma laidlawii (14,15,17). Our data provide direct values for the bilayer thicknesses of eukaryotic cell membranes and show, contrary to expectation, that, in biological membranes, the average bilayer thickness is modulated by the transmembrane domains of proteins rather than cholesterol and that lipid and protein components may not be naturally hydrophobically matched in a biological membrane.…”

mentioning

confidence: 62%

“…To measure the bilayer thickness of exocytic pathway membranes we used SXS techniques. SXS permits direct determination of the distance (d) between the highly electron-dense phosphate groups across the bilayer of membranes in solution (14,15,17). A limitation of this technique is that extramembranous protein domains and cell components containing highly electron-dense groups, such as ribosomes, can affect the quality of the scattering data (37).…”

Section: Purification and Characterization Of Membranesmentioning

confidence: 99%

“…Lipid properties, such as the degree of unsaturation and acyl chain length, have been demonstrated to modulate membrane thickness in both simple model systems and biological membranes (14)(15)(16)(17). Additionally, cholesterol has also been shown to affect the thickness of artificial bilayer systems in vitro.…”

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confidence: 99%

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Modulation of the bilayer thickness of exocytic pathway membranes by membrane proteins rather than cholesterol

Mitra

Ubarretxena-Belandia

Taguchi

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

413

307

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A biological membrane is conceptualized as a system in which membrane proteins are naturally matched to the equilibrium thickness of the lipid bilayer. Cholesterol, in addition to lipid composition, has been suggested to be a major regulator of bilayer thickness in vivo because measurements in vitro have shown that cholesterol can increase the thickness of simple phospholipid͞cholesterol bilayers. Using solution x-ray scattering, we have directly measured the average bilayer thickness of exocytic pathway membranes, which contain increasing amounts of cholesterol. The bilayer thickness of membranes of the endoplasmic reticulum, the Golgi, and the basolateral and apical plasma membranes, purified from rat hepatocytes, were determined to be 37.5 ؎ 0.4 Å, 39.5 ؎ 0.4 Å, 35.6 ؎ 0.6 Å, and 42.5 ؎ 0.3 Å, respectively. After cholesterol depletion using cyclodextrins, Golgi and apical plasma membranes retained their respective bilayer thicknesses whereas the bilayer thickness of the endoplasmic reticulum and the basolateral plasma membrane decreased by 1.0 Å. Because cholesterol was shown to have a marginal effect on the thickness of these membranes, we measured whether membrane proteins could modulate thickness. Protein-depleted membranes demonstrated changes in thickness of up to 5 Å, suggesting that (i) membrane proteins rather than cholesterol modulate the average bilayer thickness of eukaryotic cell membranes, and (ii) proteins and lipids are not naturally hydrophobically matched in some biological membranes. A marked effect of membrane proteins on the thickness of Escherichia coli cytoplasmic membranes, which do not contain cholesterol, was also observed, emphasizing the generality of our findings.

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mentioning

confidence: 62%

Section: Purification and Characterization Of Membranesmentioning

confidence: 99%

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Modulation of the bilayer thickness of exocytic pathway membranes by membrane proteins rather than cholesterol

Mitra

Ubarretxena-Belandia

Taguchi

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

413

307

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“…As is well known, the relation Io(Z)= Io(0) sin 2 0 is a good approximation for a random dispersion of membranes (Wilkins et al, 1971). It can easily be proved that this relation holds even when there is a moderate preferred orientation as in the case of Fig.…”

Section: Discussionmentioning

confidence: 65%

“…Less distinct diffuse peaks were observed for dispersions of membranes decorated by smaller numbers of uranyl ions. All these peaks could be indexed approximately by a single parameter D, as was demonstrated for other membrane dispersions by Wilkins, Blaurock & Engelman (1971). D increases with the molar ratio of uranyl acetate/lecithin: D ~ 43 ,~ at 3/100, 45 A at 1/10, 47 ./k at 1/2, 48.8 A at 1/1.…”

Section: Methodsmentioning

confidence: 67%

Structures of uranyl-decorated lecithin and lecithin–cholesterol bilayers

K¹,

Yamaguchi²,

Inoko³

et al. 1976

Acta Crystallogr Sect B

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Dipalmitoyl lecithin and dipalmitoyl lecithin-cholesterol bilayers are capable of binding about the same number of uranyl ions as lecithin molecules. Dispersions of the uranyl-decorated bilayers give very distinct continuous X-ray diffraction peaks up to the seventh order. Electron density projection onto the normal to the membrane is obtained with a resolution of about 6.5 ~. It gives two high peaks separated by 48/~, indicating that uranyl ions are bound at the surfaces of membranes in both lecithin and lecithin--cholesterol bilayers.

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X ‐Ray Scattering

Trewhella

2002

Encyclopedia of Molecular Biology

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Bilayer Structure in Membranes

Cited by 263 publications

References 23 publications

Modulation of the bilayer thickness of exocytic pathway membranes by membrane proteins rather than cholesterol

Modulation of the bilayer thickness of exocytic pathway membranes by membrane proteins rather than cholesterol

Structures of uranyl-decorated lecithin and lecithin–cholesterol bilayers

X ‐Ray Scattering

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