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Asymmetric lipid membranes: towards more realistic model systems.

Marquardt D, Geier B, Pabst G - Membranes (Basel) (2015)

Bottom Line: Despite the ubiquity of transbilayer asymmetry in natural cell membranes, the vast majority of existing research has utilized chemically well-defined symmetric liposomes, where the inner and outer bilayer leaflets have the same composition.Here, we review various aspects of asymmetry in nature and in model systems in anticipation for the next phase of model membrane studies.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstr 50/III, Graz, 8010, Austria. drew.marquardt@uni-graz.at.

ABSTRACT
Despite the ubiquity of transbilayer asymmetry in natural cell membranes, the vast majority of existing research has utilized chemically well-defined symmetric liposomes, where the inner and outer bilayer leaflets have the same composition. Here, we review various aspects of asymmetry in nature and in model systems in anticipation for the next phase of model membrane studies.

No MeSH data available.


Related in: MedlinePlus

Asymmetric lipid distribution due to vesicle size. Data were generated using the area per lipid and bilayer thickness of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) as determined by Kučerka and co-workers [34].
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membranes-05-00180-f002: Asymmetric lipid distribution due to vesicle size. Data were generated using the area per lipid and bilayer thickness of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) as determined by Kučerka and co-workers [34].

Mentions: The most common source of asymmetry, and often overlooked, in model vesicles is the non-equal number of lipid molecules between bilayer leaflets as a result of vesicle size. As the vesicle diameter decreases, the difference in leaflet surface area increases. This difference in surface area is reflected in the number of lipid molecules that exist in each leaflet, which can be calculated based on the structural details of unstressed bilayers (Figure 2). A recent coarse-grained MD simulation demonstrates membrane asymmetry by increasing the lipid density in one leaflet [30]. Lipid number density asymmetry is most easily observed experimentally by means of nuclear magnetic resonance spectroscopy [31,32]. The asymmetry has been shown via the use of a paramagnetic shift reagent, which interacts with the outer monolayer only, creating two separate signals (i.e., the inner and outer leaflet signals separate). In the special case of small unilamellar vesicles (SUV), <50 nm, the asymmetric distribution can be qualitatively observed directly, as the packing of the inner and outer monolayers is different [31,32]. This directly affects the melting transition, which is distinct from unstressed bilayers [33].


Asymmetric lipid membranes: towards more realistic model systems.

Marquardt D, Geier B, Pabst G - Membranes (Basel) (2015)

Asymmetric lipid distribution due to vesicle size. Data were generated using the area per lipid and bilayer thickness of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) as determined by Kučerka and co-workers [34].
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4496639&req=5

membranes-05-00180-f002: Asymmetric lipid distribution due to vesicle size. Data were generated using the area per lipid and bilayer thickness of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) as determined by Kučerka and co-workers [34].
Mentions: The most common source of asymmetry, and often overlooked, in model vesicles is the non-equal number of lipid molecules between bilayer leaflets as a result of vesicle size. As the vesicle diameter decreases, the difference in leaflet surface area increases. This difference in surface area is reflected in the number of lipid molecules that exist in each leaflet, which can be calculated based on the structural details of unstressed bilayers (Figure 2). A recent coarse-grained MD simulation demonstrates membrane asymmetry by increasing the lipid density in one leaflet [30]. Lipid number density asymmetry is most easily observed experimentally by means of nuclear magnetic resonance spectroscopy [31,32]. The asymmetry has been shown via the use of a paramagnetic shift reagent, which interacts with the outer monolayer only, creating two separate signals (i.e., the inner and outer leaflet signals separate). In the special case of small unilamellar vesicles (SUV), <50 nm, the asymmetric distribution can be qualitatively observed directly, as the packing of the inner and outer monolayers is different [31,32]. This directly affects the melting transition, which is distinct from unstressed bilayers [33].

Bottom Line: Despite the ubiquity of transbilayer asymmetry in natural cell membranes, the vast majority of existing research has utilized chemically well-defined symmetric liposomes, where the inner and outer bilayer leaflets have the same composition.Here, we review various aspects of asymmetry in nature and in model systems in anticipation for the next phase of model membrane studies.

View Article: PubMed Central - PubMed

Affiliation: Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstr 50/III, Graz, 8010, Austria. drew.marquardt@uni-graz.at.

ABSTRACT
Despite the ubiquity of transbilayer asymmetry in natural cell membranes, the vast majority of existing research has utilized chemically well-defined symmetric liposomes, where the inner and outer bilayer leaflets have the same composition. Here, we review various aspects of asymmetry in nature and in model systems in anticipation for the next phase of model membrane studies.

No MeSH data available.


Related in: MedlinePlus