Determination of phosphatidylglycerol asymmetry in small, unilamellar vesicles by chemical modification

Lentz, Barry R.; Alford, Dennis R.; Dombrose, Frederick A.

doi:10.1021/bi00553a003

Cited by 41 publications

(50 citation statements)

References 25 publications

(42 reference statements)

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“…What is remarkable about the transmembrane distribution of GalCer is its strong preference for the inner leaflet when present at 1 or 2 mol % in POPC SUVs. Earlier studies of PE and PG (see Introduction) revealed just the opposite behavior in that these lipids strongly preferred the outer leaflet of PC SUVs (29,30). Only when present at 10 mol % (or more) in PC SUVs did PE and PG assume transmembrane distributions that can be rationalized by the structural parameters associated with their overall shape, charge, and hydration (22,29,30).…”

Section: Discussionmentioning

confidence: 97%

“…Earlier studies of PE and PG (see Introduction) revealed just the opposite behavior in that these lipids strongly preferred the outer leaflet of PC SUVs (29,30). Only when present at 10 mol % (or more) in PC SUVs did PE and PG assume transmembrane distributions that can be rationalized by the structural parameters associated with their overall shape, charge, and hydration (22,29,30). The preferential localization of low mole fractions of PE and PG to the outer leaflet of PC SUVs has been explained as a general lattice response linked to the "looser" molecular packing of the outer leaflet of PC SUVs (30).…”

Section: Discussionmentioning

confidence: 98%

“…However, lipid geometric shapes alone do not satisfactorily account for the transbilayer distributions observed when PC SUVs contain low mole fractions of either PE or phosphatidylglycerol (PG). In this case, disproportionately higher amounts of PE or PG are observed in the SUV outer leaflet, putatively because of generalized lattice packing effects (29,30). Together, these studies show that investigating lipid transbilayer distributions in vesicles provides an effective means to gain insights into the interrelationship between lipid structure and membrane curvature.…”

mentioning

confidence: 80%

“…Only when present at 10 mol % (or more) in PC SUVs did PE and PG assume transmembrane distributions that can be rationalized by the structural parameters associated with their overall shape, charge, and hydration (22,29,30). The preferential localization of low mole fractions of PE and PG to the outer leaflet of PC SUVs has been explained as a general lattice response linked to the "looser" molecular packing of the outer leaflet of PC SUVs (30). Our results clearly show that GalCer does not conform to the PE/PG transmembrane localizations in fluid PC bilayers previously reported for highly curved phosphoglyceride vesicles.…”

Section: Discussionmentioning

confidence: 99%

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Sphingomyelin Modulates the Transbilayer Distribution of Galactosylceramide in Phospholipid Membranes

Mattjus¹,

Malewicz²,

Valiyaveettil³

et al. 2002

Journal of Biological Chemistry

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The interrelationships among sphingolipid structure, membrane curvature, and glycosphingolipid transmembrane distribution remain poorly defined despite the emerging importance of sphingolipids in curved regions and vesicle buds of biomembranes. Here, we describe a novel approach to investigate the transmembrane distribution of galactosylceramide in phospholipid small unilamellar vesicles by 13 C NMR spectroscopy. Quantitation of the transbilayer distribution of [6-13 C]galactosylceramide (99.8% isotopic enrichment) was achieved by exposure of vesicles to the paramagnetic ion, Mn 2؉ . The data show that [6-13 C]galactosylceramide prefers (70%) the inner leaflet of phosphatidylcholine vesicles. Increasing the sphingomyelin content of the 1-palmitoyl-2-oleoyl-phosphatidylcholine vesicles shifted galactosylceramide from the inner to the outer leaflet. The amount of galactosylceramide localized in the inner leaflet decreased from 70% in pure 1-palmitoyl-2-oleoyl-phosphatidylcholine vesicles to only 40% in 1-palmitoyl-2-oleoyl-phosphatidylcholine/ sphingomyelin (1:2) vesicles. The present study demonstrates that sphingomyelin can dramatically alter the transbilayer distribution of a monohexosylceramide, such as galactosylceramide, in 1-palmitoyl-2-oleoylphosphatidylcholine/sphingomyelin vesicles. The results suggest that sphingolipid-sphingolipid interactions that occur even in the absence of cholesterol play a role in controlling the transmembrane distributions of cerebrosides.Sphingolipids participate in a number of important cellular processes that require membrane budding, fission, or vesiculation (1, 2). Examples include infectious processes involving bacterial toxin and envelope virus entry into cells (3, 4), exosomal antigen presentation (5), and processes related to the terminal stages of apoptosis (6). Many recent investigations, by this laboratory and others, have focused on the in-plane lateral interactions among sphingolipids, cholesterol, and other membrane lipids (7-10). As a result, significant new insights into sphingolipid organization in membranes have emerged, including the identification and characterization of sphingolipid-enriched, liquid-ordered microdomains, often referred to as rafts (11-13). With so much emphasis on lipid lateral interactions, studies of sphingolipid transmembrane distribution have been relatively few (14), and the interrelationships among sphingolipid structure, membrane curvature, and glycosphingolipid transmembrane distribution remain poorly understood (15).Much of what is currently known about the mechanical forces affecting membrane curvature has been achieved by investigations of phosphoglyceride model membranes (16). The elastic constants associated with a fluid membrane are the bending elastic modulus and the spontaneous curvature (17, 18). The bending elastic modulus is the resistance of membranes to curvature or the bending rigidity, whereas the spontaneous curvature is the inherent curvature of an unconstrained membrane section and changes with lipid structure. Bec...

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Section: Discussionmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 98%

mentioning

confidence: 80%

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

Sphingomyelin Modulates the Transbilayer Distribution of Galactosylceramide in Phospholipid Membranes

Mattjus¹,

Malewicz²,

Valiyaveettil³

et al. 2002

Journal of Biological Chemistry

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“…Yet, in addition to the salt concentration and pH in solution, the composition of mixed lipids ought to affect the distribution of a component lipid in the vesicle. There have been reports presenting different views on the asymmetry of certain phospholipids in the vesicle [14,15,18,19]. However, the methods used might have led to different conclusions.…”

Section: Discussionmentioning

confidence: 99%

31P and19F NMR studies of glycophorin-reconstituted membranes: Preferential interaction of glycophorin with phosphatidylserine

Ong

1984

J. Membrain Biol.

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Glycophorin A, a major glycoprotein of the erythrocyte membrane, has been incorporated into small unilamellar vesicles composed of a variety of pure and mixed phospholipids. Nuclear spin labels including 31P and 19F have been used at natural abundance or have been synthetically incorporated in lipids to act as probes of lipid-protein interaction. Interactions produce broadening of resonances in several cases and it can be used to demonstrate preferential interaction of certain lipids with glycophorin. 31P and 19F probes show a strong preferential interaction of glycophorin with phosphatidylserine over phosphatidylcholine. There is some evidence that interactions are more pronounced at the inner surface of the bilayer and these results are rationalized in terms of the asymmetric distribution of protein and lipid.

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Liposomes: Preparation, Characterization, and Preservation

Lichtenberg

Barenholz

1988

Methods of Biochemical Analysis

244

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Determination of phosphatidylglycerol asymmetry in small, unilamellar vesicles by chemical modification

Cited by 41 publications

References 25 publications

Sphingomyelin Modulates the Transbilayer Distribution of Galactosylceramide in Phospholipid Membranes

Sphingomyelin Modulates the Transbilayer Distribution of Galactosylceramide in Phospholipid Membranes

31P and19F NMR studies of glycophorin-reconstituted membranes: Preferential interaction of glycophorin with phosphatidylserine

Liposomes: Preparation, Characterization, and Preservation

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