Temperature dependence of proton permeation through a voltage-gated proton channel. Planar Lipid Bilayers: Methods and Applications. Academic Press Limited, London Perfusion of an Aqueous SolutionA. The perfusion method. A micropipette was inserted into a bubble. Injection of a hydrophilic substance followed by the drain to the bubble-holding pipette yielded rapid perfusion.
SNAREs — engines for membrane fusion
An additional micropipette allows injection of the original bubble solution, by which the hydrophilic substance can be applied as a pulse-like fashion with an arbitrary pulse duration. Neutral pH jump immediately attenuated the channel activity with single channel decaying process in the inset. The current recovered immediately upon acidic pH jump. In Fig.
Membrane perfusion of hydrophobic substances around channels embedded in the contact bubble bilayer. The Membrane Perfusion MethodA. The water-in-oil droplet system is governed by three rules. First, one of the leaflets of the bilayer is contiguous to the monolayer lining the bubble, and lipids are freely diffusible between two phases. Second, the hydrophobic membrane interior is contiguous to the surrounding bulk oil phase, and an addition of hydrophobic substances in the oil phase leads to transfer towards the membrane interior.
Third, integral membrane proteins remain in the bilayer and never move to the monolayer. Membrane perfusion of a hydrophobic substance. A representative current trace of the KcsA channel upon cholesterol perfusion. For hydrophobic substances to reach the interior of conventional membrane, they must be dissolved in an aqueous solution, which are then partitioned into the membrane. In the CBB, Rule 2, the membrane interior is open to the bulk oil phase, is applied. Hydrophobic substances are dissolved in hexadecane, and this solution is sprayed over the CBB from the oil phase Fig.
Advantages of the CBB method include its manipulability of bubbles, by which monolayer-bilayer transitions are allowed. Here we briefly summarize applications of manipulability of the bilayer. Unlike other water-in-oil bilayer methods, the bubbles in CBB are maintained by pressure, and this pressure can be readily changed in either a symmetric or asymmetric manner. For example, bilayer tension has been applied by injecting the solution into a droplet.
Activation of the mechanosensitive ion channel MscL by mechanical stimulation of supported droplet-hydrogel bilayers. Sci Rep. Piezo1 channels are inherently mechanosensitive. Cell Reports , 17 , — To date, no one has imagined what happens to channel activity when a bilayer is detached and membrane embedded channels are withdrawn from the bilayer. Surely, one would imagine the channel activity would be lost in the absence of the bilayer membrane. However, in the case of the peptide channel polytheonamide B pTB , channel activity immediately resumed when the monolayers were re-attached.
A channel-forming peptide toxin: polytheonamide from marine sponge Theonella swinhoei. Nippon Yakurigaku Zasshi , Suppl. Freeze-fracture cytochemistry in cell biology. Methods Cell Biol.
In the CBB method, each monolayer can be treated separately prior to bilayer formation. Here we show an example of using a one-bubble application. As shown in the detach-attach procedure, pTB is located at the monolayer interface, with its hydrophilic C-terminus anchored in the aqueous solution. Thus, pTB should be transferred to the monolayer once it has been added in the oil phase. When the two bubbles were separated from each other, and pTB was added exclusively to one of the bubbles, they were both distributed at the monolayer interface.
Thus, once two bubbles are attached, the hydrophobic N-terminus spans the bilayer and forms a channel, and the orientation of the channel is determined by the bubble with the pTB addition. Detach-attach and channel activities. When detached a , no channel current flowed. During this process, pTB was uprooted from the bilayer and located at the interface of the right monolayer. Upon re-attachment c , the current amplitude recovered to the original level. The detach-attach can be repeated. Application of high membrane potential broke the bilayer, and two bubbles were fused d , by which pTB originally located at the surface of the right bubble diffused to the left side of the fused bubble.
Afterward, upon creating a bilayer, pTB was located in both monolayers, and the orientation of the membrane-inserted pTB became random.
Biomembranes are highly complex systems involving bilayer asymmetry and heterogenous phases, in which dynamic interplay between the bilayer and channels is ongoing. The recent development of water-in-oil bilayers, including DIB and CBB, allows researchers to manipulate the bilayer more freely.
FUSION-COMPETENT STATE INDUCED BY A C-TERMINAL HIV-1 FUSION PEPTIDE IN CHOLESTEROL-RICH MEMBRANES
Various maneuvers in the monolayer, such as forming an asymmetric membrane, as well as mechanical maneuvers, have opened to researchers an unprecedented variety of experimental venues for studying channel-membrane interactions. Membrane manipulation is not limited to physical and chemical procedures conducted on the bilayer itself, but now include alterations to membrane-incorporated channels, such as channel forming substances, which may deform the membrane upon channel formation.
More than a pore: The interplay of pore-forming proteins and lipid membranes. Channel formation and membrane deformation via sterol-aided polymorphism of amphidinol 3. Already have an account? Login in here. Biological and Pharmaceutical Bulletin. Journal home Advance online publication Journal issue Featured articles About the journal.
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Current Topics: Reviews. Keywords: ion channel , lipid bilayer , contact bubble bilayer , droplet interface bilayer , single-channel recording. Conflict of Interest. Various Reconstitution Methods Detergent-solubilized channels were purified and reconstituted into liposomes. Principles for the Formation of a Lipid Bilayer Using the Water-in-Oil Method Once a water droplet is formed in the bulk oil phase containing phospholipids, a monolayer is formed at the oil—water interface.
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Liposome and Water-in-Oil Droplet A. Perfusion of an Aqueous Solution A. The Membrane Perfusion Method A. One of the leaflets of the bilayer membrane is continuous with the monolayer on the relevant bubble. The membrane interior is contiguous to the bulk oil phase. The integral membrane proteins diffuse but remain in the membrane. Supplementary materials. Share this page. Register Already have an account? Small 4 7 , — Zheng, T.
Controlling the rate of coiled coil driven membrane fusion. Chemical Communications 49 35 , — A non-zipper-like tetrameric coiled coil promotes membrane fusion. RSC Advances 6 10 , — Daudey, G. Langmuir 33 43 , — Versluis, F. Journal of the American Chemical Society 21 , — Coiled-coil driven membrane fusion: zipper-like vs. Faraday Discussions 0 , — Crone, S.
International Journal of Molecular Sciences, 19 1 Rabe, M. Biophysical Journal 10 , — Segrest, J. A molecular theory of lipid-protein interactions in the plasma lipoproteins. FEBS Lett 38 3 , — Amphipathic helix motif: classes and properties. Proteins 8 2 , — Mishra, V.
pricaddileke.tk Journal of Biological Chemistry 10 , — Jensen, M. Membrane curvature sensing by amphipathic helices: a single liposome study using alpha-synuclein and annexin B J Biol Chem 49 , — The fusion of membranes and vesicles: Pathway and energy barriers from dissipative particle dynamics. Biophysical Journal 96 7 , — Markvoort, A.
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Chernomordik and M. Kozlov, Editors. Academic Press. Marrink, S. Coarse grained model for semiquantitative lipid simulations.