Structural diversity of sphingomyelin microdomains

Giocondi, Marie-Cécile; Boichot, Sylvie; Plénat, Thomas; Grimellec, C Christian Le

doi:10.1016/j.ultramic.2003.11.002

Cited by 40 publications

(31 citation statements)

References 35 publications

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“…Such morphologies have the appearance of spinodal decomposition often encountered in the phase separation of polymer thin films (Bassereau et al, 1993;Sung et al, 1996;Karim et al, 2002). Although this particular topography, depending on the presence of SM, was previously reported for SM/phosphatidylcholine binary mixtures (Giocondi et al, 2004a) imaged at this temperature, it was not observed in control samples containing either no ( Figure 1E) or limited amount of incorporated BIAP (not shown). By heating the BIAP-loaded samples to 358C, the SLB recovered a 'flat' bilayer topography ( Figure 1C), characterized by the presence of large thick (!5 nm) domains, labeled 3 on the figure, with a grainy aspect protruding from a rough, grainy matrix (2) surrounding few $2 nm thinner small smooth domains (1, arrows).…”

Section: Resultssupporting

confidence: 48%

“…Their very irregular shape was most likely due to the coexistence at this temperature of liquid ordered and gel phases in the ordered domains (de Almeida et al, 2003;Veatch and Keller, 2005). Virtual section across ordered domains, with the smooth bilayer as a reference, gave ordered domains of irregular heights often significantly exceeding 6-7 nm, that is, the sum of the fully extended hydrophilic part of the BIAP when normal to the bilayer ($5 nm) (Le Du et al, 2001), plus the thickness excess of the ordered phases relative to the fluid phase (Giocondi et al, 2004a;Milhiet et al, 2002b). This suggested the existence of height undulation of the ordered phase even at this low temperature.…”

Section: Biap Distribution Between Ordered and Fluid Domainsmentioning

confidence: 99%

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Temperature‐dependent localization of GPI‐anchored intestinal alkaline phosphatase in model rafts

Giocondi

Besson

Dosset

et al. 2007

J of Molecular Recognition

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In plasma membranes, most of glycosylphosphatidylinositol (GPI)-anchored proteins would be associated with rafts, a category of ordered microdomains enriched in sphingolipids and cholesterol (Ch). They would be also concentrated in the detergent resistant membranes (DRMs), a plasma membrane fraction extracted at low temperature. Preferential localization of GPI-anchored proteins in these membrane domains is essentially governed by their high lipid order, as compared to their environment. Changes in the temperature are expected to modify the membrane lipid order, suggesting that they could affect the distribution of GPI-anchored proteins between membrane domains. Validity of this hypothesis was examined by investigating the temperature-dependent localization of the GPI-anchored bovine intestinal alkaline phophatase (BIAP) into model raft made of palmitoyloleoylphosphatidylcholine/sphingomyelin/cholesterol (POPC/SM/Chl) supported membranes. Atomic force microscopy (AFM) shows that the inserted BIAP is localized in the SM/Chl enriched ordered domains at low temperature. Above 30 degrees C, BIAP redistributes and is present in both the 'fluid' POPC enriched and the ordered SM/Chl domains. These data strongly suggest that in cells the composition of plasma membrane domains at low temperature differs from that at physiological temperature.

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Section: Resultssupporting

confidence: 48%

Section: Biap Distribution Between Ordered and Fluid Domainsmentioning

confidence: 99%

Temperature‐dependent localization of GPI‐anchored intestinal alkaline phosphatase in model rafts

Giocondi

Besson

Dosset

et al. 2007

J of Molecular Recognition

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“…For example, Silvius and coworkers showed differential partitioning of SM into SM/CHOL domains (Wang and Silvius, 2000) and partitioning of lipidated peptides into ordered lipid domains (Wang et al, 2001). Many contributors to the field discussed a vital role for cholesterol in the formation and stability of such membrane rafts (Radhakrishnan et al, 2000;Xu et al, 2001;Veatch and Keller, 2003) and initial imaging of raft structures by atomic force microscopy was reported (Rinia et al, 2001;Giocondi et al, 2004). But interestingly, an attenuating effect of cholesterol on domain formation was also reported for renal brush border membranes (Milhiet et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Imaging of the domain organization in sphingomyelin and phosphatidylcholine monolayers

Prenner¹,

Honsek²,

Hoenig³

et al. 2007

Chemistry and Physics of Lipids

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The lateral organization of biomembranes has gained significant interest when the fluid mosaic model was challenged by the model of "lipid rafts". Several lipid classes like cholesterol and sphingolipids are considered to be essential for their formation. Here we investigate the lateral domain formation in binary mixtures of sphingomyelin and phosphatidylcholine. Both are major lipid components of lipoproteins and mammalian cell membranes at various molar ratios. Surface pressure-area isotherms and surface potential-area isotherms of monolayers composed of these lipids clearly indicated non-ideal mixing. In addition, Brewster angle microscopy provided a well-suited approach to image the formation of lateral domains. These images demonstrated that pure sphingomyelin forms very stable finger-like domains that exhibit a distinct internal organization suggesting an anisotropic orientation of the acyl side chains. Similar behavior was found for mixtures containing more than 60 mol% sphingomyelin. With increasing content of phosphatidylcholine the domain size decreased and the surface pressure, where domain formation occurred, increased. At lower sphingomyelin content (30-60 mol%) rather round-shaped, smaller domains were observed. Thus, the potential of sphingomyelin domains as potentially important building blocks for actual domains that could be building blocks for raft formation is suggested, even without the presence of cholesterol. In addition, these observations may suggest a role for the distinct molar ratio of these key lipids frequently found in physiologically relevant particles such as low and high density lipoproteins or the outer leaflet of the human erythrocyte membrane.

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“…These structural differences between diverse types of membranes create significant modifications in their mechanical properties that in turn can lead to segregation of transmembrane proteins (19,20). Atomic force microscopy experiments (21) have revealed the existence of a marked structural diversity of gel phase SMenriched microdomains, which can adopt mesoscopic structures of varied sizes and shapes, for both single mixtures as well as different PC species (e.g. DOPC and palmitoyloleoylphosphatidylcholine (POPC)).…”

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confidence: 99%

Plasmon-waveguide Resonance Studies of Lateral Segregation of Lipids and Proteins into Microdomains (Rafts) in Solid-supported Bilayers

Salamon

Devanathan

Alves

et al. 2005

Journal of Biological Chemistry

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Plasmon-waveguide resonance (PWR) spectroscopy has been used to examine solid-supported lipid bilayers consisting of dioleoylphosphatidylcholine (DOPC), palmitoyloleoylphosphatidylcholine (POPC), sphingomyelin (SM), and phosphatidylcholine/SM binary mixtures. Spectral simulation of the resonance curves demonstrated an increase in bilayer thickness, long-range order, and molecular packing density in going from DOPC to POPC to SM single component bilayers, as expected based on the decreasing level of unsaturation in the fatty acyl chains. DOPC/SM and POPC/SM binary mixtures yielded PWR spectra that can be ascribed to a superposition of two resonances corresponding to microdomains (rafts) consisting of phosphatidylcholine-and SM-rich phases coexisting within a single bilayer. These were formed spontaneously over time as a consequence of lateral phase separation. Each microdomain contained a small proportion (<20%) of the other lipid component, which increased their kinetic and thermodynamic stability. Incorporation of a glycosylphosphatidylinositol-linked protein (placental alkaline phosphatase) occurred within each of the single component bilayers, although the insertion was less efficient into the DOPC bilayer. Incorporation of placental alkaline phosphatase into a DOPC/SM binary bilayer occurred with preferential insertion into the SM-rich phase, although the protein incorporated into both phases at higher concentrations. These results demonstrate the utility of PWR spectroscopy to provide insights into raft formation and protein sorting in model lipid membranes.The classical textbook model of biomembrane structure, usually referred to as the fluid-mosaic model, envisions a twodimensional solution of integral membrane proteins in a homogeneous lipid solvent, albeit one composed of many molecular lipid species and possessing inside-outside asymmetry with respect to both protein and lipid components. However, in recent years, there has been a growing recognition that lateral segregation of lipids and proteins occurs within regions of biomembranes called rafts (cf. Refs. 1 and 2). Along with caveolae, which are invaginations of raft regions stabilized by interactions with oligomers of the protein caveolin, these microdomains have been suggested to play important roles in cell polarity, protein sorting, signal transduction, and membrane trafficking (cf. Refs. 3 and 4).One of the key properties of rafts is their high content of sphingomyelin (SM) 1 and cholesterol, which leads to their being organized into what are referred to as liquid-ordered domains. These are characterized by being more highly ordered and somewhat thicker than the surrounding liquid-disordered regions of the membrane. This is a consequence of the ordering influence of cholesterol and the presence in SM of a larger proportion of saturated fatty acyl chains. However, it should be noted that studies of model membranes have shown that microdomain formation also occurs in phosphatidylcholine (PC)/SM mixtures in the absence of cholesterol (2). These li...

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Structural diversity of sphingomyelin microdomains

Cited by 40 publications

References 35 publications

Temperature‐dependent localization of GPI‐anchored intestinal alkaline phosphatase in model rafts

Temperature‐dependent localization of GPI‐anchored intestinal alkaline phosphatase in model rafts

Imaging of the domain organization in sphingomyelin and phosphatidylcholine monolayers

Plasmon-waveguide Resonance Studies of Lateral Segregation of Lipids and Proteins into Microdomains (Rafts) in Solid-supported Bilayers

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