On the Origin of Sphingolipid/Cholesterol-Rich Detergent-Insoluble Cell Membranes:  Physiological Concentrations of Cholesterol and Sphingolipid Induce Formation of a Detergent-Insoluble, Liquid-Ordered Lipid Phase in Model Membranes

Biochemistry ◽  
1997 ◽  
Vol 36 (36) ◽  
pp. 10944-10953 ◽  
Author(s):  
Sharmin N. Ahmed ◽  
Deborah A. Brown ◽  
Erwin London
Keyword(s):  
Cell Membranes ◽  
Model Membranes ◽  
Lipid Phase ◽  
Liquid Ordered

scholarly journals Synthesis and Characterization of a Novel Green Cationic Polyfluorene and Its Potential Use as a Fluorescent Membrane Probe

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 938 ◽  
Author(s):  
Rebeca Vázquez-Guilló ◽  
María Martínez-Tomé ◽  
Zehra Kahveci ◽  
Ivan Torres ◽  
Alberto Falco ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Membrane Surface ◽  
Aqueous Media ◽  
Coupling Reaction ◽  
Model Membranes ◽  
Lipid Phase ◽  
Fluorescent Properties ◽  
Membrane Probe ◽  
Fluorescence Efficiency ◽  
Potential Use

In the present work, we have synthesized a novel green-emitter conjugated polyelectrolyte Copoly-{[9,9-bis(6′-N,N,N-trimethylammonium)hexyl]-2,7-(fluorene)-alt-4,7-(2-(phenyl) benzo[d] [1,2,3] triazole)} bromide (HTMA-PFBT) by microwave-assisted Suzuki coupling reaction. Its fluorescent properties have been studied in aqueous media and in presence of model membranes of different composition, in order to explore its ability to be used as a green fluorescent membrane probe. The polyelectrolyte was bound with high affinity to the membrane surface, where it exhibited high fluorescence efficiency and stability. HTMA-PFBT showed lower affinity to zwitterionic membranes as compared to anionic ones, as well as a more external location, near the membrane-aqueous interface. Fluorescence microscopy studies confirmed the interaction of HTMA-PFBT with the model membranes, labelling the lipid bilayer without perturbing its morphology and showing a clear preference towards anionic systems. In addition, the polyelectrolyte was able to label the membrane of bacteria and living mammalian cells, separately. Finally, we explored if the polyelectrolyte can function also as a sensitive probe able of detecting lipid-phase transitions. All these results suggest the potential use of HTMA-PFBT as a green membrane marker for bioimaging and selective recognition of bacteria cell over mammalian ones and as a tool to monitor changes in physical state of lipid membranes.

scholarly journals Liquid ordered phase in cell membranes evidenced by a hydration-sensitive probe: Effects of cholesterol depletion and apoptosis

2010 ◽  
Vol 1798 (7) ◽  
pp. 1436-1443 ◽  
Author(s):  
Sule Oncul ◽  
Andrey S. Klymchenko ◽  
Oleksandr A. Kucherak ◽  
Alexander P. Demchenko ◽  
Sophie Martin ◽  
...  
Keyword(s):  
Cell Membranes ◽  
Cholesterol Depletion ◽  
Liquid Ordered

scholarly journals Membrane thickness, lipid phase and sterol type are determining factors in the permeability of membranes to small solutes

2021 ◽  
Author(s):  
Jacopo Frallicciardi ◽  
Josef Melcr ◽  
Pareskevi Siginou ◽  
Siewert Marrink ◽  
Bert Poolman
Keyword(s):  
Lipid Membranes ◽  
Lipid Phase ◽  
Membrane Thickness ◽  
Bacterial Cells ◽  
Concentration Gradients ◽  
Kinetic Measurements ◽  
Systematic Analysis ◽  
Liquid Ordered ◽  
Dynamics Simulations

Abstract Cell membranes provide a selective semi-permeable barrier to the passive transport of molecules. This property differs greatly between organisms. While the cytoplasmic membrane of bacterial cells is highly permeable for weak acids and glycerol, yeasts can maintain large concentration gradients. Here we show that such differences can arise from the physical state of the plasma membrane. By combining stopped-flow kinetic measurements with molecular dynamics simulations, we performed a systematic analysis of the permeability through synthetic lipid membranes to obtain detailed molecular insight into the permeation mechanisms. While membrane thickness is an important parameter for the permeability through fluid membranes, the largest differences occur when the membranes transit from the liquid-disordered to liquid-ordered and/or to gel state. By comparing our results with in vivo measurements from yeast, we conclude that the yeast membrane exists in a highly ordered and rigid state, which is comparable to synthetic saturated DPPC-sterol membranes.

scholarly journals Protein sorting by lipid phase-like domains supports emergent signaling function in B lymphocyte plasma membranes

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Matthew B Stone ◽  
Sarah A Shelby ◽  
Marcos F Núñez ◽  
Kathleen Wisser ◽  
Sarah L Veatch
Keyword(s):  
Plasma Membranes ◽  
B Lymphocyte ◽  
Membrane Lipids ◽  
Super Resolution ◽  
Cell Receptor ◽  
Biochemical Networks ◽  
Lipid Phase ◽  
Intact Cells ◽  
Signaling Function ◽  
Liquid Ordered

Diverse cellular signaling events, including B cell receptor (BCR) activation, are hypothesized to be facilitated by domains enriched in specific plasma membrane lipids and proteins that resemble liquid-ordered phase-separated domains in model membranes. This concept remains controversial and lacks direct experimental support in intact cells. Here, we visualize ordered and disordered domains in mouse B lymphoma cell membranes using super-resolution fluorescence localization microscopy, demonstrate that clustered BCR resides within ordered phase-like domains capable of sorting key regulators of BCR activation, and present a minimal, predictive model where clustering receptors leads to their collective activation by stabilizing an extended ordered domain. These results provide evidence for the role of membrane domains in BCR signaling and a plausible mechanism of BCR activation via receptor clustering that could be generalized to other signaling pathways. Overall, these studies demonstrate that lipid mediated forces can bias biochemical networks in ways that broadly impact signal transduction.

Patterns of non-electrolyte permeability

1969 ◽  
Vol 172 (1028) ◽  
pp. 227-271 ◽  
Keyword(s):  
Partition Coefficients ◽  
Cell Membranes ◽  
Membrane Lipids ◽  
Intermolecular Forces ◽  
Lipid Phase ◽  
Water Molecules ◽  
Polar Groups ◽  
Polar Solutes ◽  
In Transit ◽  
Coupling Phenomena

Reflexion coefficients (σ’s) for epithelial cells of rabbit gall-bladder for 206 non-electrolytes have been measured and analysed. In general, σ’s decrease from 1.0 to 0 with increasing lipid :water partition coefficients, so that the intermolecular forces governing permeation of most non-electrolytes are the same as those governing partition between a bulk lipid phase and water. The two classes of deviations to this pattern are related to the specific structure of cell membranes. First, highly branched molecules have higher σ’s (permeate more slowly) than expected from partition coefficients, an effect attributed to an isotropy of membrane lipids. Secondly, the smallest, most lipid-insoluble molecules have lower σ’s (permeate more readily) than expected, and are also anomalous in that: effects of changes in their structure on or disobey Overton’s rules; the inverse relation between or and temperature is less steep for them than for other so lutes; and their σ’s are little affected by decreases in pH which increase σ’s of other solutes. These anomalies are interpreted to mean that small polar solutes in transit through the membrane interact minimally or not at all with hydrocarbon tails of membrane lipids, but in stead follow a route formed by localized concentrations of membrane polar groups associated with ‘frozen’ water molecules, where the coupling phenomena between permeating water, ions, and small polar-electrolytes observed in cell membranes may also occur.

scholarly journals The Effect of Transmembrane Protein Shape on Surrounding Lipid Domain Formation by Wetting

Biomolecules ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 729 ◽  
Author(s):  
Molotkovsky ◽  
Galimzyanov ◽  
Batishchev ◽  
Akimov
Keyword(s):  
Phase Separation ◽  
Transmembrane Protein ◽  
Lipid Phase ◽  
Lipid Domains ◽  
Domain Formation ◽  
Cellular Membranes ◽  
Lipid Domain ◽  
Liquid Ordered ◽  
Lipid Environment ◽  
Protein Shape

Signal transduction through cellular membranes requires the highly specific and coordinated work of specialized proteins. Proper functioning of these proteins is provided by an interplay between them and the lipid environment. Liquid-ordered lipid domains are believed to be important players here, however, it is still unclear whether conditions for a phase separation required for lipid domain formation exist in cellular membranes. Moreover, membrane leaflets are compositionally asymmetric, that could be an obstacle for the formation of symmetric domains spanning the lipid bilayer. We theoretically show that the presence of protein in the membrane leads to the formation of a stable liquid-ordered lipid phase around it by the mechanism of protein wetting by lipids, even in the absence of conditions necessary for the global phase separation in the membrane. Moreover, we show that protein shape plays a crucial role in this process, and protein conformational rearrangement can lead to changes in the size and characteristics of surrounding lipid domains.

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