Shapes of finite two-dimensional lipid domains

McConnell, Harden M.; Moy, Vincent T.

doi:10.1021/j100326a053

Cited by 243 publications

(270 citation statements)

References 0 publications

Supporting

Mentioning

259

Contrasting

Order By: Relevance

“…The two contributions have quite different functional forms, and we find that, depending upon the value of A b = K/µR, it may be preferable either to keep the defect at the origin or to allow it to migrate towards the boundary. Maintaining 0 < r d < R − ξ we find the following behavior of (24) within this class of textures,…”

Section: B Defect Insidementioning

confidence: 78%

Stability of texture and shape of circular domains of Langmuir monolayers

Pettey

Lubensky

1999

Phys. Rev. E

View full text Add to dashboard Cite

Finite domains of a Langmuir monolayer in a phase with tilted molecules can be modeled by a simple elastic free energy of an XY order parameter with isotropic and anisotropic line tension terms. The domains can and often do contain nontrivial textures, which in turn influence the shape of the domains. Herein we investigate the properties of a simplified isotropic model with a single elastic constant. For circular domains a first-order phase transition is found between two distinct textures: an exterior defect (or "virtual boojum") texture, and an interior defect texture. Starting with a circular domain and either of these two textures as a ground state, we find shape instabilities develop that depend on the elastic constants and line tensions in the simplified model. In both cases a necessary but not sufficient condition for the onset of shape instabilities is the possibility for a local negative effective line tension to develop from the anisotropic line tension term.

show abstract

Section: B Defect Insidementioning

confidence: 78%

Stability of texture and shape of circular domains of Langmuir monolayers

Pettey

Lubensky

1999

Phys. Rev. E

View full text Add to dashboard Cite

show abstract

“…Moreover, a detailed analysis of such shapes can be utilized to quantify molecular interactions between the monolayer constituents. 21,25,26 To assess NPY association with phospholipid membrane surfaces, we started with dual-label experiments in which L-rhod B-DHPE (∼ 0.4 mol% with respect to total lipid) was used to label the lipid monolayer while CF-hNPY (10 mol% with respect to total peptide) was used to visualize the peptide distribution at the surface. Since the absorption and emission spectra of these two labels are sufficiently separated, this enables a discrimination of the different labels using appropriate filter sets.…”

Section: Fluorescence Microscopymentioning

confidence: 99%

Interaction of the Neurotransmitter, Neuropeptide Y, with Phospholipid Membranes: Film Balance and Fluorescence Microscopy Studies

Dyck

Lösche

2006

J. Phys. Chem. B

View full text Add to dashboard Cite

The association of neuropeptide Y (NPY) with air/water interfaces and with phospholipid monolayers on water subphases and on physiological buffer has been investigated. Surface pressure (π) vs. molecular area (A) relations of the peptide at water surfaces depend on the concentration of the spreading solutions. Independent of that concentration, they show a transition from a low-density state to a high-density state at π ∼ 12 mN/m. Similar features are observed in the NPY adsorption to preformed monolayers (Δπ(t→∞) as a function of π i = π(t=0) where t = 0 signifies the time of peptide injection). The transition is also observed in cospread lipid/NPY monolayers and is interpreted as the exclusion of the peptide from the surface layer. The reproducibility of the isotherms after expansion suggests that cospread lipid/peptide monolayers are thermodynamically stable and that the peptide remains associated with the monolayer after exclusion from the lipid surface.A comparison of NPY association with zwitterionic and with anionic lipids, as well as a comparison of the interactions on pure water and on physiological buffer, suggests that electrostatic attraction plays a major role in the energetics of peptide binding to the membrane surface. Dual label fluorescence microscopy demonstrates that the peptide associates preferentially with the disordered liquid-condensed (LC) monolayer phase and also suggests that it self-aggregates upon exceeding a critical surface concentration. A NPY variant with a distorted α-helix interacts with the surface as strongly as the natural NPY but expands the monolayers more. This suggests that the helix motif in the peptide is more important for the interaction with the receptor than for binding of the peptide to the membrane surface. In context, these observations attribute a specific role to the membrane in funneling the signal peptide to its membrane receptor.

show abstract

“…It is known that the orientational order and chirality of lipid headgroups in the monolayers at the air-water interface are reflected in the domain shape of the lipid (61,(72)(73)(74). Domain shapes are thought to be determined by a competition between line tension (that tends to stabilize isotropic circular domains) and long-range dipole-dipole repulsion between lipid molecules (that tends to stabilize elongated domains) (75). Thus, charged lipids generally tend to form elongated domains.…”

Section: Differential Scanning Calorimetry (Dsc)mentioning

confidence: 99%

Differential Membrane Packing of Stereoisomers of Bis(monoacylglycero)phosphate

et al. 2006

View full text Add to dashboard Cite

Bis(monoacylglycero)phosphate (BMP) reveals an unusual sn-1,sn-1′ stereoconfiguration of glycerophosphate. We synthesized sn- (3-myristoyl-2-hydroxy)glycerol-1-phospho-sn-1′-(3′-myristoyl-2′-hydroxy)glycerol (1,1′-DMBMP) and characterized the thermotropic phase behavior and membrane structure, in comparison with those of the corresponding sn-3:sn-1′ stereoisomer (3,1′-DMBMP), by means of differential scanning calorimetry (DSC), small-and wide-angle X-ray scattering (SAXS and WAXS, respectively), pressure-area (π-A) isotherms, epifluorescence microscopy of monolayers, and molecular dynamics (MD) simulations. In DSC, these lipids exhibited weakly energetic broad peaks with an onset temperature of 9°C for 1,1′-DMBMP and 18°C for 3,1′-DMBMP. In addition, a highly cooperative, strongly energetic transition peak was observed at ∼40°C for 1,1′-DMBMP and ∼42°C for 3,1′-DMBMP. These results are supported by the observation that 1,1′-DMBMP exhibited a larger phase transition pressure (π c ) than 3,1′-DMBMP. Small-and wide-angle X-ray scattering measurements identified these small and large energetic transitions as a quasi-crystalline (L c1 )-quasi-crystalline with different tilt angle (L c2 ) phase transition and an L c2 -L R main phase transition, respectively. X-ray measurements also revealed that these DMBMPs undergo an unbinding at the main phase transition temperature. The MD simulations estimated stronger hydrogen bonding formation in the 3,1′-DMBMP membrane than in 1,1′-DMBMP, supporting the experimental data.Bis(monoacylglycero)phosphate, also known as lysobisphosphatidic acid (LBPA), was first described in pig and rabbit pulmonary alveolar macrophages by Body and Gray (1). BMPs comprise less than 1% of the total phospholipids in most mammalian cells (2, 3). However, the content is increased to 15% in late endosomes (4). In the specific internal membrane domains of this organelle, this lipid comprises more than 70% of the total phospholipids (5).Because of the high level of accumulation in late endosomes, BMP is assumed to be important for the structural and functional integrity of the organelle. Indeed, a series of experiments has demonstrated that agents that perturb BMP induce alterations in the sorting and trafficking of proteins and/or the receptor in late endosomes accompanied by structural changes of the late edonsome organelle (4, 6) along with abnormal accumulation of cholesterol (7). Moreover, BMP is found to be essential for the activator-stimulated hydrolysis of ganglioside G M1 (8) and G M2 (9) and for the hydrolysis of ceramide by acid ceramidase (10).BMP has unique structural characteristics with various fatty acid compositions depending on the source. Whereas all other mammalian phospholipids display a sn-3-glycerophosphate stereoconfiguration, BMP possesses an sn-1:sn-1′ structure and one acyl group attached to each of the glycerol moieties (11-13). An sn-3:sn-1′ isomer has also been reported for BMP in BHK cells (14). However, the sn-3:sn-1′ isomer in mammalian cells is postulated to be...

show abstract

Shapes of finite two-dimensional lipid domains

Cited by 243 publications

References 0 publications

Stability of texture and shape of circular domains of Langmuir monolayers

Stability of texture and shape of circular domains of Langmuir monolayers

Interaction of the Neurotransmitter, Neuropeptide Y, with Phospholipid Membranes: Film Balance and Fluorescence Microscopy Studies

Differential Membrane Packing of Stereoisomers of Bis(monoacylglycero)phosphate

Contact Info

Product

Resources

About