On the diffusion of circular domains on a spherical vesicle

Aliaskarisohi, Saeedeh; Tierno, Pietro; Dhar, Prajnaparamita; Khattari, Z. Y.; Blaszczynski, M.; Fischer, Thomas M.

doi:10.1017/s0022112010000650

Cited by 15 publications

(21 citation statements)

References 38 publications

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“…This result was utilized in a recent experimental study of the diffusion of a raftlike domain, the viscosity of which would be different from that of the outer membrane. 20) For a liquid domain having an arbitrary viscosity, Ramachandran et al calculated the drag coefficient by using the frictional coefficient between the membrane and the ambient fluids. 21) We assume each of the ambient fluids to occupy a semiinfinite region, and consider their dynamics without using the frictional coefficient.…”

Section: Introductionmentioning

confidence: 99%

Drag Coefficient of a Liquid Domain in a Fluid Membrane

Fujitani

2011

J. Phys. Soc. Jpn.

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We calculate the drag coefficient of a circular liquid domain in a flat fluid membrane, which is surrounded by threedimensional fluids, by using the Stokes approximation. Taking into account the difference between the membrane viscosities inside and outside the domain, we obtain an integral equation involving a parameter, which is defined as unity minus the ratio of the latter viscosity to the former. We solve the equation up to the linear order with respect to the parameter to calculate the drag coefficient numerically. Its derivative with respect to the domain viscosity, evaluated when there is no difference between the membrane viscosities, is shown to almost vanish.

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Section: Introductionmentioning

confidence: 99%

Drag Coefficient of a Liquid Domain in a Fluid Membrane

Fujitani

2011

J. Phys. Soc. Jpn.

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“…It has been shown that attaching an artificial cytoskeleton made of actin or a tubulin homolog alters the shape and position of the ordered domains (16,17). The analysis of the diffusion of lipid domains observed on lipid monolayers (18,19) and GUVs (20)(21)(22) revealed that the drag force experienced by the ordered lipid domains is governed by the viscosity of the fluid phase and the hydrodynamic coupling to the aqueous phase.…”

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Size and mobility of lipid domains tuned by geometrical constraints

Schütte

Mey

Enderlein

et al. 2017

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

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In the plasma membrane of eukaryotic cells, proteins and lipids are organized in clusters, the latter ones often called lipid domains or "lipid rafts." Recent findings highlight the dynamic nature of such domains and the key role of membrane geometry and spatial boundaries. In this study, we used porous substrates with different pore radii to address precisely the extent of the geometric constraint, permitting us to modulate and investigate the size and mobility of lipid domains in phase-separated continuous pore-spanning membranes (PSMs). Fluorescence video microscopy revealed two types of liquid-ordered (l o ) domains in the freestanding parts of the PSMs: (i) immobile domains that were attached to the pore rims and (ii) mobile, round-shaped l o domains within the center of the PSMs. Analysis of the diffusion of the mobile l o domains by video microscopy and particle tracking showed that the domains' mobility is slowed down by orders of magnitude compared with the unrestricted case. We attribute the reduced mobility to the geometric confinement of the PSM, because the drag force is increased substantially due to hydrodynamic effects generated by the presence of these boundaries. Our system can serve as an experimental test bed for diffusion of 2D objects in confined geometry. The impact of hydrodynamics on the mobility of enclosed lipid domains can have great implications for the formation and lateral transport of signaling platforms. diffusion | hydrodynamics | lipid rafts | membrane dynamics | pore-spanning membranes T he plasma membrane of eukaryotic cells compartmentalizes into lipid domains that enable the selective recruitment of specific proteins (1, 2). These domains are an important feature for regulating biological functions such as apical sorting, protein trafficking, and the clustering of proteins during signaling. The most prominent concept for membrane organization, the lipid raft theory, relates lipid phase separation [driven by interactions between cholesterol (chol), sphingolipids, and saturated phospholipids] to membrane protein partitioning and regulation (2, 3). Lipid domains such as rafts are difficult to observe in biological membranes due to their small size and dynamic nature (4). To understand the phase separation phenomena and the dynamics of lipid domains, the phase behavior of giant plasma membrane-derived vesicles (5, 6) as well as ternary model membranes containing two phospholipid species and chol have been investigated extensively in the last decade. In these model membranes, lipid phase separation between liquid-ordered (l o ) and liquid-disordered (l d ) phases is readily observed at low temperature (7-9). These raft-like domains grow several micrometers in size in giant unilamellar vesicles (GUVs) (7), while their mobility is preserved, whereas lipid domains in supported lipid bilayers are smaller but are largely immobile and do not form energy-minimized round shapes (10). Explanations for the size difference of lipid domains in native plasma membranes and model membranes ran...

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“…Most rheological investigations of membranes have been made by observing Brownian motion in flat lipid membranes and spherical vesicles [3,5,6] as well as in liquid crystal films [7,8], with the mobility of the inclusions calculated from the diffusion coefficient by means of the Einstein relation. This approach requires a model describing the relation between the mobility and such physical parameters as the inclusion size and the viscosities of the membrane and the surrounding fluid.…”

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confidence: 99%