Fabrication of phospholipid bilayer-coated microchannels for on-chip immunoassays.
AuthorsYang T, Jung S, Mao H, Cremer PS
JournalAnal Chem
PubMed ID11199961
'Herein we describe a new class of microfluidic immunoassays based upon solid supported lipid bilayers. Two-dimensionally fluid bilayer material, which can accommodate multivalent binding between surface-bound ligands and aqueous receptors, was coated on the surface of poly(dimethylsiloxane) microchannels. The bilayers contained dinitrophenyl (DNP)-conjugated lipids for binding with bivalent anti-DNP antibodies. ... More
Restriction of receptor movement alters cellular response: physical force sensing by EphA2.
AuthorsSalaita K, Nair PM, Petit RS, Neve RM, Das D, Gray JW, Groves JT,
JournalScience
PubMed ID20223987
'Activation of the EphA2 receptor tyrosine kinase by ephrin-A1 ligands presented on apposed cell surfaces plays important roles in development and exhibits poorly understood functional alterations in cancer. We reconstituted this intermembrane signaling geometry between live EphA2-expressing human breast cancer cells and supported membranes displaying laterally mobile ephrin-A1. Receptor-ligand binding, ... More
Formation of supported phospholipid bilayers on molecular surfaces: role of surface charge density and electrostatic interaction.
AuthorsCha T, Guo A, Zhu XY
JournalBiophys J
PubMed ID16449198
'Electrostatic interaction is known to play important roles in the adsorption of charged lipids on oppositely charged surfaces. Here we show that, even for charge neutral (zwitterionic) lipids, electrostatic interaction is critical in controlling the adsorption and fusion of lipid vesicles to form supported phospholipid bilayers (SPBs) on surfaces. We ... More
Optical detection of ion-channel-induced proton transport in supported phospholipid bilayers.
AuthorsYang TH, Yee CK, Amweg ML, Singh S, Kendall EL, Dattelbaum AM, Shreve AP, Brinker CJ, Parikh AN,
JournalNano Lett
PubMed ID17629349
'The integration of ion-channel transport functions with responses derived from nanostructured and nanoporous silica mesophase materials is demonstrated. Patterned thin-film mesophases consisting of alternating hydrophilic nanoporous regions and hydrophobic nanostructured regions allow for spatially localized proton transport via selective dimerization of gramicidin in lipid bilayers formed on the hydrophilic regions. ... More
The location of fluorescence probes with charged groups in model membranes.
AuthorsKachel K, Asuncion-Punzalan E, London E
JournalBiochim Biophys Acta
PubMed ID9814853
'The location of commonly used charged fluorescent membrane probes in membranes was determined in order to: (1) investigate the relationship between the structure of hydrophobic molecules and their depth within membranes; and (2) aid interpretation of experiments in which these fluorescent probes are used to examine membrane structure. Membrane depth ... More
Effect of average phospholipid curvature on supported bilayer formation on glass by vesicle fusion.
AuthorsHamai C, Yang T, Kataoka S, Cremer PS, Musser SM
JournalBiophys J
PubMed ID16299084
'The adsorption of large unilamellar vesicles composed of various combinations of phosphatidylcholine, phosphatidylethanolamine (PE), monomethyl PE, and dimethyl PE (PE-Me2) onto a glass surface was studied using fluorescence microscopy. The average lipid geometry within the vesicles, described mathematically by the average intrinsic curvature, C(0,ave), was methodically altered by changing the ... More
A concentration-dependent mechanism by which serum albumin inactivates replacement lung surfactants.
AuthorsWarriner HE, Ding J, Waring AJ, Zasadzinski JA
JournalBiophys J
PubMed ID11806925
'Endogenous lung surfactant, and lung surfactant replacements used to treat respiratory distress syndrome, can be inactivated during lung edema, most likely by serum proteins. Serum albumin shows a concentration-dependent surface pressure that can exceed the respreading pressure of collapsed monolayers in vitro. Under these conditions, the collapsed surfactant monolayer can ... More
Characterizing submicron vesicles with wavelength-resolved fluorescence in flow cytometry.
AuthorsFuller RR, Sweedler JV
JournalCytometry
PubMed ID8891444
'Individual synthetic vesicles 0.1-1.0 micron in diameter are sized by using single-particle fluorescence emission spectra obtained in a custom sheath flow cell with an imaging spectrograph and a charge-coupled device. Data are acquired at 1 Hz, with limits of detection (3 sigma) less than 6.0 x 10(3) and 1.0 x ... More
Novel Fusogenic Liposomes for Fluorescent Cell Labeling and Membrane Modification.
AuthorsCsisza´r A, Hersch N, Dieluweit S, Biehl R, Merkel R, Hoffmann B,
JournalBioconjug Chem
PubMed ID20184308
'Efficient delivery of biomolecules into membranes of living cells as well as cell surface modifications are major biotechnological challenges. Here, novel liposome systems based on neutral and cationic lipids in combination with lipids modified by aromatic groups are introduced for such applications. The fusion efficiency of these liposome systems was ... More
Surface specific kinetics of lipid vesicle adsorption measured with a quartz crystal microbalance.
AuthorsKeller CA, Kasemo B
JournalBiophys J
PubMed ID9726940
'We have measured the kinetics of adsorption of small (12.5-nm radius) unilamellar vesicles onto SiO2, oxidized gold, and a self-assembled monolayer of methyl-terminated thiols, using a quartz crystal microbalance (QCM). Simultaneous measurements of the shift in resonant frequency and the change in energy dissipation as a function of time provide ... More
The actin-binding protein hisactophilin binds in vitro to partially charged membranes and mediates actin coupling to membranes.
AuthorsBehrisch A, Dietrich C, Noegel AA, Schleicher M, Sackmann E
JournalBiochemistry
PubMed ID7578133
'The interaction of the actin-binding protein hisactophilin from Dictyostelium discoideum amoebae to partially charged lipid membranes composed of mixtures of L-alpha-dimyristoylphosphatidylcholine (DMPC) with L-alpha-dimyristoylphosphatidylglycerol (DMPG) and L-alpha-phosphatidylinositol 4,5-bisphosphate (PIP2) is studied by film balance experiments, microfluorescence, and lateral diffusion measurements at low ionic strengths (approximately 20 mM). Excess surface concentrations ... More
Brownian ratchets: molecular separations in lipid bilayers supported on patterned arrays.
Authorsvan Oudenaarden A, Boxer SG
JournalScience
PubMed ID10446046
'Brownian ratchets use a time-varying asymmetric potential that can be applied to separate diffusing particles or molecules. A new type of Brownian ratchet, a geometrical Brownian ratchet, has been realized. Charged, fluorescently labeled phospholipids in a two-dimensional fluid bilayer were driven in one direction by an electric field through a ... More
Spatial organization of bacteriorhodopsin in model membranes. Light-induced mobility changes.
AuthorsKahya N, Wiersma DA, Poolman B, Hoekstra D
JournalJ Biol Chem
PubMed ID12167614
'Bacteriorhodopsin is a proton-transporting membrane protein in Halophilic archaea, and it is considered a prototype of membrane transporters and a model for G-protein-coupled receptors. Oligomerization of the protein has been reported, but it is unknown whether this feature is correlated with, for instance, light activation. Here, we have addressed this ... More
Early endosomal SNAREs form a structurally conserved SNARE complex and fuse liposomes with multiple topologies.
AuthorsZwilling D, Cypionka A, Pohl WH, Fasshauer D, Walla PJ, Wahl MC, Jahn R
JournalEMBO J
PubMed ID17159904
'SNARE proteins mediate membrane fusion in eukaryotic cells. They contain conserved SNARE motifs that are usually located adjacent to a C-terminal transmembrane domain. SNARE motifs spontaneously assemble into four helix bundles, with each helix belonging to a different subfamily. Liposomes containing SNAREs spontaneously fuse with each other, but it is ... More
High refractive index substrates for fluorescence microscopy of biological interfaces with high z contrast.
AuthorsAjo-Franklin CM, Kam L, Boxer SG
JournalProc Natl Acad Sci U S A
PubMed ID11717428
'Total internal reflection fluorescence microscopy is widely used to confine the excitation of a complex fluorescent sample very close to the material on which it is supported. By working with high refractive index solid supports, it is possible to confine even further the evanescent field, and by varying the angle ... More
Sec16p potentiates the action of COPII proteins to bud transport vesicles.
AuthorsSupek F, Madden DT, Hamamoto S, Orci L, Schekman R
JournalJ Cell Biol
PubMed ID12235121
'SEC16 encodes a 240-kD hydrophilic protein that is required for transport vesicle budding from the ER in Saccharomyces cerevisiae. Sec16p is tightly and peripherally bound to ER membranes, hence it is not one of the cytosolic proteins required to reconstitute transport vesicle budding in a cell-free reaction. However, Sec16p is ... More
Differential partitioning of maternal fatty acid and phospholipid in neonate mosquito larvae.
AuthorsAtella GC, Shahabuddin M
JournalJ Exp Biol
PubMed ID12409488
'In animals, lipids are a source of energy, cell membrane components, signaling pathway modulators and emulsifying agents. In egg-laying animals, maternal yolk lipids, imported into the egg before laying, are metabolized or distributed in the developing embryo to serve these functions. Studies with birds, reptiles and insects have described lipid ... More
Trypanosoma rangeli uptakes the main lipoprotein from the hemolymph of its invertebrate host.
AuthorsFolly E, Cunha e Silva NL, Lopes AH, Silva-Neto MA, Atella GC
JournalBiochem Biophys Res Commun
PubMed ID14521946
'During its life cycle Trypanosoma rangeli crosses the hemolymph of its invertebrate host. In the present study, we demonstrate for the first time the uptake of lipophorin (Lp), the main lipid-transporting particle of insect hemolymph. We observed that living T. rangeli parasites uptake lipids from both 32P- and 3H-, or ... More
'Alzheimer''s disease is the most common cause of dementia and is widely believed to be due to the accumulation of beta-amyloid peptides (Abeta) and their interaction with the cell membrane. Abetas are hydrophobic peptides derived from the amyloid precursor proteins by proteolytic cleavage. After cleavage, these peptides are involved in ... More
Arrays of mobile tethered vesicles on supported lipid bilayers.
AuthorsYoshina-Ishii C, Boxer SG
JournalJ Am Chem Soc
PubMed ID12656589
Interaction of NBD-talin with lipid monolayers. A film balance study.
AuthorsDietrich C, Goldmann WH, Sackmann E, Isenberg G
JournalFEBS Lett
PubMed ID8504857
Fluorescently labelled smooth muscle talin like native talin interacts with negatively or partly negatively charged lipid monolayers. This was measured in time/area diagrams using the film balance technique combined with fluorescence imaging after double photolabelling of talin and phospholipids. ... More
Electric field-induced concentration gradients in planar supported bilayers.
AuthorsGroves JT, Boxer SG
JournalBiophys J
PubMed ID8580340
A simple method of generating electric field-induced concentration gradients in planar supported bilayers has been developed. Gradients of charged, fluorescently labeled probes were visualized by epifluorescence microscopy and could be observed at field strengths as low as 1 V/cm. Steady-state concentration gradients can be described by a simple competition between ... More
Effect of electric field gradients on lipid monolayer membranes.
AuthorsLee KY, McConnell HM
JournalBiophys J
PubMed ID7612817
Externally applied nonuniform electric fields can strongly affect thermodynamic phases in a lipid monolayer when applied under conditions of temperature, pressure, and composition that are near phase boundaries. Under such conditions nonuniform applied fields can produce or suppress phase separations. Field-induced phase-separated domains have sizes that are in good agreement ... More
Biomolecular interactions at phospholipid-decorated surfaces of liquid crystals.
AuthorsBrake JM, Daschner MK, Luk YY, Abbott NL
JournalScience
PubMed ID14684814
The spontaneous assembly of phospholipids at planar interfaces between thermotropic liquid crystals and aqueous phases gives rise to patterned orientations of the liquid crystals that reflect the spatial and temporal organization of the phospholipids. Strong and weak specific-binding events involving proteins at these interfaces drive the reorganization of the phospholipids ... More
Detection of molecular interactions at membrane surfaces through colloid phase transitions.
AuthorsBaksh MM, Jaros M, Groves JT,
JournalNature
PubMed ID14712272
The molecular architecture of-and biochemical processes within--cell membranes play important roles in all living organisms, with many drugs and infectious disease agents targeting membranes. Experimental studies of biochemical reactions on membrane surfaces are challenging, as they require a membrane environment that is fluid (like cell membranes) but nevertheless allows for ... More
Effects of linker sequences on vesicle fusion mediated by lipid-anchored DNA oligonucleotides.
AuthorsChan YH, van Lengerich B, Boxer SG,
JournalProc Natl Acad Sci U S A
PubMed ID19164559
Synthetic lipid-oligonucleotide conjugates inserted into lipid vesicles mediate fusion when one population of vesicles displays the 5'-coupled conjugate and the other the 3'-coupled conjugate, so that anti-parallel hybridization allows the membrane surfaces to come into close proximity. Improved assays show that lipid mixing proceeds more quickly and to a much ... More
Single-molecule fluorescence studies of a PH domain: new insights into the membrane docking reaction.
AuthorsKnight JD, Falke JJ,
JournalBiophys J
PubMed ID19167305
Proteins containing membrane targeting domains play essential roles in many cellular signaling pathways. However, important features of the membrane-bound state are invisible to bulk methods, thereby hindering mechanistic analysis of membrane targeting reactions. Here we use total internal reflection fluorescence microscopy (TIRFM), combined with single particle tracking, to probe the ... More
Single giant vesicle rupture events reveal multiple mechanisms of glass-supported bilayer formation.
AuthorsHamai C, Cremer PS, Musser SM,
JournalBiophys J
PubMed ID17189305
The formation of supported lipid bilayers (SLBs) on glass from giant unilamellar vesicles (GUVs) was studied using fluorescence microscopy. We show that GUV rupture occurs by at least four mechanisms, including 1), spontaneous rupture of isolated GUVs yielding almost heart-shaped bilayer patches (asymmetric rupture); 2), spontaneous rupture of isolated GUVs ... More
Single-step process to reconstitute cell membranes on solid supports.
AuthorsMager MD, Melosh NA,
JournalLangmuir
PubMed ID20205459
A new technique is presented to create supported lipid bilayers from whole cell lipids without the use of detergent or solvent extraction. In a modification of the bubble collapse deposition (BCD) technique, an air bubble is created underwater and brought into contact with a population of cells. The high-energy air/water ... More
How curved membranes recruit amphipathic helices and protein anchoring motifs.
Lipids and several specialized proteins are thought to be able to sense the curvature of membranes (MC). Here we used quantitative fluorescence microscopy to measure curvature-selective binding of amphipathic motifs on single liposomes 50-700 nm in diameter. Our results revealed that sensing is predominantly mediated by a higher density of ... More
Lipid vesicle adsorption versus formation of planar bilayers on solid surfaces.
AuthorsNollert P, Kiefer H, Jähnig F
JournalBiophys J
PubMed ID8534815
The absorption and spreading behavior of lipid vesicles composed of either palmitoyloleoylphosphatidylcholine (POPC) or Escherichia coli lipid upon contact with a glass surface was examined by fluorescence measurements. Fluorescently labeled lipids were used to determine 1) the amount of lipid adsorbed at the surface, 2) the extent of fusion of ... More
Micropatterning fluid lipid bilayers on solid supports.
AuthorsGroves JT, Ulman N, Boxer SG
JournalScience
PubMed ID9005848
Lithographically patterned grids of photoresist, aluminum oxide, or gold on oxidized silicon substrates were used to partition supported lipid bilayers into micrometer-scale arrays of isolated fluid membrane corrals. Fluorescently labeled lipids were observed to diffuse freely within each membrane corral but were confined by the micropatterned barriers. The concentrations of ... More
A neutron reflectivity study of polymer-modified phospholipid monolayers at the solid-solution interface: polyethylene glycol-lipids on silane-modified substrates.
AuthorsKuhl TL, Majewski J, Wong JY, Steinberg S, Leckband DE, Israelachvili JN, Smith GS
JournalBiophys J
PubMed ID9788930
The structure of polymer-decorated phospholipid monolayers at the solid-solution interface was investigated using neutron reflectometry. The monolayers were composed of distearoylphosphatidylethanolamine (DSPE) matrixed with varying amounts of DSPE-PEG (DSPE with polyethylene glycol covalently grafted to its headgroup). Mixed lipid monolayers were Langmuir-Blodgett deposited onto hydrophobic quartz or silicon substrates, previously ... More
Membrane flux through the pore formed by a fusogenic viral envelope protein during cell fusion.
AuthorsTse FW, Iwata A, Almers W
JournalJ Cell Biol
PubMed ID8486735
We have investigated the mechanism of cell fusion mediated by HA, the fusogenic hemagglutinin of the Influenza viral envelope. Single erythrocytes (RBCs) were attached to fibroblasts expressing the HA on their cell surface, and fusion of the paired cells was triggered by rapid acidification. The RBC membrane was stained with ... More
Statistical pattern matching facilitates the design of polyvalent inhibitors of anthrax and cholera toxins.
AuthorsRai P, Padala C, Poon V, Saraph A, Basha S, Kate S, Tao K, Mogridge J, Kane RS
JournalNat Biotechnol
PubMed ID16633350
Numerous biological processes involve the recognition of a specific pattern of binding sites on a target protein or surface. Although ligands displayed by disordered scaffolds form stochastic rather than specific patterns, theoretical models predict that recognition will occur between patterns that are characterized by similar or "matched" statistics. Endowing synthetic ... More
Lipid headgroup discrimination by antimicrobial peptide LL-37: insight into mechanism of action.
AuthorsNeville F, Cahuzac M, Konovalov O, Ishitsuka Y, Lee KY, Kuzmenko I, Kale GM, Gidalevitz D
JournalBiophys J
PubMed ID16299073
Interaction of the human antimicrobial peptide LL-37 with lipid monolayers has been investigated by a range of complementary techniques including pressure-area isotherms, insertion assay, epifluorescence microscopy, and synchrotron x-ray scattering, to analyze its mechanism of action. Lipid monolayers were formed at the air-liquid interface to mimic the surface of the ... More
A common pathway for the uptake of surfactant lipids by alveolar cells.
AuthorsPoelma DL, Ju MR, Bakker SC, Zimmermann LJ, Lachmann BF, van Iwaarden JF
JournalAm J Respir Cell Mol Biol
PubMed ID14644915
The uptake of different surfactant lipids-dipalmitoylphosphatidylcholine (DPPC), phosphatidylglycerol (PG), or phosphatidylinositol (PI)-and liposomes with a surfactant-like composition by alveolar type II cells (alveolar type II cells) and macrophages (alveolar macrophages) was studied in vitro. Fluorescent-labeled liposomes containing either 86% of the studied lipid, i.e., DPPC, PG, PI, and 6% labeled ... More
Nod factors integrate spontaneously in biomembranes and transfer rapidly between membranes and to root hairs, but transbilayer flip-flop does not occur.
AuthorsGoedhart J, Röhrig H, Hink MA, van Hoek A, Visser AJ, Bisseling T, Gadella TW
JournalBiochemistry
PubMed ID10451386
Three novel nodulation (Nod) factors were synthesized from chitotetraose and three structurally different fluorescent BODIPY-tagged fatty acids. With fluorescence spectroscopic and microscopic techniques, the following aspects were studied: whether these amphiphilic molecules insert in membranes, whether they transfer between different membranes, and whether they are able to transfer from a ... More
Direct observation of poloxamer 188 insertion into lipid monolayers.
AuthorsMaskarinec SA, Hannig J, Lee RC, Lee KY
JournalBiophys J
PubMed ID11867460
P188, a triblock copolymer of the form poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) helps seal electroporated cell membranes, arresting the leakage of intracellular materials from the damaged cells. To explore the nature of the interaction between P188 and cell membranes, we have constructed a model system that assesses the ability of P188 ... More
Functional immobilization of a DNA-binding protein at a membrane interface via histidine tag and synthetic chelator lipids.
AuthorsDietrich C, Boscheinen O, Scharf KD, Schmitt L, Tampé R
JournalBiochemistry
PubMed ID8573564
The coupling of a DNA-binding protein to self-organized lipid monolayers is examined at the air-water interface by means of film balance techniques and epifluorescence microscopy. We used two recombinant species of the heat shock factor HSF24 which differ only in a carboxy-terminal histidine tag that interacts specifically with the nickel-chelating ... More
Molecular forces between membranes displaying neutral glycosphingolipids: evidence for carbohydrate attraction.
AuthorsYu ZW, Calvert TL, Leckband D
JournalBiochemistry
PubMed ID9484224
The surface force apparatus was used to determine the fundamental forces governing the adhesion between mixed bilayer membranes comprising lactosyl ceramide (LacCer) and di-tridecanoyl-phosphatidyl choline. Forces between membranes were quantified as a function of the glycolipid surface densities, which ranged from 0 to 30 mol %. Control measurements of the ... More
Lateral diffusion coefficients in membranes measured by resonance energy transfer and a new algorithm for diffusion in two dimensions.
AuthorsKusba J, Li L, Gryczynski I, Piszczek G, Johnson M, Lakowicz JR
JournalBiophys J
PubMed ID11867452
We describe measurements of lateral diffusion in membranes using resonance energy transfer. The donor was a rhenium (Re) metal-ligand complex lipid, which displays a donor decay time near 3 micros. The long donor lifetime resulted in an ability to measure lateral diffusion coefficient below 10(-8) cm(2)/s. The donor decay data ... More
Location of the membrane-docking face on the Ca2+-activated C2 domain of cytosolic phospholipase A2.
AuthorsNalefski EA, Falke JJ
JournalBiochemistry
PubMed ID9922129
Docking of C2 domains to target membranes is initiated by the binding of multiple Ca2+ ions to a conserved array of residues imbedded within three otherwise variable Ca2+-binding loops. We have located the membrane-docking surface on the Ca2+-activated C2 domain of cPLA2 by engineering a single cysteine substitution at 16 ... More
Membrane protein microarrays.
AuthorsFang Y, Frutos AG, Lahiri J
JournalJ Am Chem Soc
PubMed ID11890761
This paper describes the fabrication of microarrays consisting of G protein-coupled receptors (GPCRs) on surfaces coated with gamma-aminopropylsilane (GAPS). Microspots of model membranes on GAPS-coated surfaces were observed to have several desired properties-high mechanical stability, long range lateral fluidity, and a thickness corresponding to a lipid bilayer in the bulk ... More
Resonance energy transfer microscopy: observations of membrane-bound fluorescent probes in model membranes and in living cells.
AuthorsUster PS, Pagano RE
JournalJ Cell Biol
PubMed ID3771633
A conventional fluorescence microscope was modified to observe the sites of resonance energy transfer (RET) between fluorescent probes in model membranes and in living cells. These modifications, and the parameters necessary to observe RET between membrane-bound fluorochromes, are detailed for a system that uses N-4-nitrobenzo-2-oxa-1,3-diazole (NBD) or fluorescein as the ... More
Architecture and function of membrane proteins in planar supported bilayers: a study with photosynthetic reaction centers.
AuthorsSalafsky J, Groves JT, Boxer SG
JournalBiochemistry
PubMed ID8942639
We present a simple and convenient method for creating fluid supported bilayers which contain oriented and functional photosynthetic reaction centers (RCs). The supported bilayers are prepared by fusion of proteoliposomes with a glass surface. The proteoliposomes are prepared by spontaneous insertion of RCs into preformed small, unilamellar vesicles. The RCs ... More
Lessons learned from clustering of fluorinated glycolipids on selectin ligand function in cell rolling.
AuthorsSchumacher G, Bakowsky U, Gege C, Schmidt RR, Rothe U, Bendas G
JournalBiochemistry
PubMed ID16503644
Selectin-induced leukocyte rolling along the endothelium is an essential step in the cellular immune response. Since clustering of binding epitopes is thought to be crucial for selectin-ligand interaction, we focused on requirements of ligand clusters in a flow chamber study. Neoglycolipids bearing the binding epitope sialyl Lewis X (sLeX) were ... More
A columnar phase of dendritic lipid-based cationic liposome-DNA complexes for gene delivery: hexagonally ordered cylindrical micelles embedded in a DNA honeycomb lattice.
AuthorsEwert KK, Evans HM, Zidovska A, Bouxsein NF, Ahmad A, Safinya CR
JournalJ Am Chem Soc
PubMed ID16551108
Gene therapy holds great promise as a future approach to fighting disease and is explored in worldwide clinical trials. Cationic liposome (CL)-DNA complexes are a prevalent nonviral delivery vector, but their efficiency requires improvement and the understanding of their mechanism of action is incomplete. As part of our effort to ... More
Reconstitution of membrane proteins into giant unilamellar vesicles via peptide-induced fusion.
AuthorsKahya N, Pécheur EI, de Boeij WP, Wiersma DA, Hoekstra D
JournalBiophys J
PubMed ID11509360
In this work, we present a protocol to reconstitute membrane proteins into giant unilamellar vesicles (GUV) via peptide-induced fusion. In principle, GUV provide a well-defined lipid matrix, resembling a close-to-native state for biophysical studies, including optical microspectroscopy, of transmembrane proteins at the molecular level. Furthermore, reconstitution in this manner would ... More
Adhesion-induced receptor segregation and adhesion plaque formation: A model membrane study.
AuthorsKloboucek A, Behrisch A, Faix J, Sackmann E
JournalBiophys J
PubMed ID10512849
A model system to study the control of cell adhesion by receptor-mediated specific forces, universal interactions, and membrane elasticity is established. The plasma membrane is mimicked by reconstitution of homophilic receptor proteins into solid supported membranes and, together with lipopolymers, into giant vesicles with the polymers forming an artificial glycocalix. ... More
Purification, functional reconstitution, and characterization of the Saccharomyces cerevisiae isoprenylcysteine carboxylmethyltransferase Ste14p.
AuthorsAnderson JL, Frase H, Michaelis S, Hrycyna CA
JournalJ Biol Chem
PubMed ID15611058
Numerous proteins, including Ras, contain a C-terminal CAAX motif that directs a series of three sequential post-translational modifications: isoprenylation of the cysteine residue, endoproteolysis of the three terminal amino acids and alpha-carboxyl methylesterification of the isoprenylated cysteine. This study focuses on the isoprenylcysteine carboxylmethyltransferase (Icmt) enzyme from Saccharomyces cerevisiae, Ste14p, ... More
Charging the quantum capacitance of graphene with a single biological ion channel.
Authors
JournalACS Nano
PubMed ID24754625
Black Lipid Membranes: Challenges in Simultaneous Quantitative Characterization by Electrophysiology and Fluorescence Microscopy.
AuthorsTsemperouli M, Amstad E, Sakai N, Matile S, Sugihara K
JournalLangmuir
PubMed ID31244250
'Horizontal black lipid membranes (BLMs) enable optical microscopy to be combined with the electrophysiological measurements for studying ion channels, peptide pores, and ionophores. However, a careful literature review reveals that simultaneous fluorescence and electrical recordings in horizontal BLMs have been rarely reported for an unclear reason, whereas many works employ ... More
Two forms of Opa1 cooperate to complete fusion of the mitochondrial inner-membrane.
Authors
JournalElife
PubMed ID31922487
Spherical-supported membranes as platforms for screening against membrane protein targets.
Authors
JournalAnal Biochem
PubMed ID29545094
Simple sugars shape giant vesicles into multispheres with many membrane necks.
Authors
JournalSoft Matter
PubMed ID31912078
Formation of phase separated vesicles by double layer cDICE.
Authors
JournalSoft Matter
PubMed ID31663090
Erythro-VLPs: Anchoring SARS-CoV-2 spike proteins in erythrocyte liposomes.
Authors
JournalPLoS One
PubMed ID35275926
SARS-CoV-2 requires cholesterol for viral entry and pathological syncytia formation.
Authors
JournalElife
PubMed ID33890572
Membrane curvature regulates the spatial distribution of bulky glycoproteins.
Authors
JournalNat Commun
PubMed ID35654773
Alterations in the properties of the cell membrane due to glycosphingolipid accumulation in a model of Gaucher disease.
Authors
JournalSci Rep
PubMed ID29317695
Use of the supported membrane tube assay system for real-time analysis of membrane fission reactions.
AuthorsDar S, Kamerkar SC, Pucadyil TJ
JournalNat Protoc
PubMed ID28125102
The process of membrane fission is fundamental to diverse cellular processes such as nutrient uptake, synaptic transmission and organelle biogenesis, and it involves the localized application of curvature stress to a tubular membrane intermediate, forcing it to undergo scission. Alternative techniques for creating such substrates necessitate the use of micromanipulators ... More
Arp2/3 complex-mediated actin assembly at cell membranes drives the formation of protrusions or endocytic vesicles. To identify the mechanism by which different membrane deformations can be achieved, we reconstitute the basic membrane deformation modes of inward and outward bending in a confined geometry by encapsulating a minimal set of cytoskeletal ... More
K-Ras4B Remains Monomeric on Membranes over a Wide Range of Surface Densities and Lipid Compositions.
AuthorsChung JK, Lee YK, Denson JP, Gillette WK, Alvarez S, Stephen AG, Groves JT
JournalBiophys J
PubMed ID29320680
Ras is a membrane-anchored signaling protein that serves as a hub for many signaling pathways and also plays a prominent role in cancer. The intrinsic behavior of Ras on the membrane has captivated the biophysics community in recent years, especially the possibility that it may form dimers. In this article, ... More
Molecular Discrimination between Two Conformations of Sphingomyelin in Plasma Membranes.
AuthorsEndapally S, Frias D, Grzemska M, Gay A, Tomchick DR, Radhakrishnan A
JournalCell
PubMed ID30712872
Sphingomyelin and cholesterol are essential lipids that are enriched in plasma membranes of animal cells, where they interact to regulate membrane properties and many intracellular signaling processes. Despite intense study, the interaction between these lipids in membranes is not well understood. Here, structural and biochemical analyses of ostreolysin A (OlyA), ... More