scholarly journals Lipid Membrane State Change by Catalytic Protonation and the Implications for Synaptic Transmission

Membranes ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 5
Author(s):  
Christian Fillafer ◽  
Yana S. Koll ◽  
Matthias F. Schneider
Keyword(s):  
Lateral Pressure ◽  
Lipid Membrane ◽  
Pressure Change ◽  
Postsynaptic Membrane ◽  
Receptor Protein ◽  
State Change ◽  
Protein Interface ◽  
Cholinergic Synapses ◽  
Membrane Models ◽  
Hydrolysis Of

In cholinergic synapses, the neurotransmitter acetylcholine (ACh) is rapidly hydrolyzed by esterases to choline and acetic acid (AH). It is believed that this reaction serves the purpose of deactivating ACh once it has exerted its effect on a receptor protein (AChR). The protons liberated in this reaction, however, may by themselves excite the postsynaptic membrane. Herein, we investigated the response of cell membrane models made from phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidic acid (PA) to ACh in the presence and absence of acetylcholinesterase (AChE). Without a catalyst, there were no significant effects of ACh on the membrane state (lateral pressure change ≤0.5 mN/m). In contrast, strong responses were observed in membranes made from PS and PA when ACh was applied in presence of AChE (>5 mN/m). Control experiments demonstrated that this effect was due to the protonation of lipid headgroups, which is maximal at the pK (for PS: pKCOOH≈5.0; for PA: pKHPO4−≈8.5). These findings are physiologically relevant, because both of these lipids are present in postsynaptic membranes. Furthermore, we discussed evidence which suggests that AChR assembles a lipid-protein interface that is proton-sensitive in the vicinity of pH 7.5. Such a membrane could be excited by hydrolysis of micromolar amounts of ACh. Based on these results, we proposed that cholinergic transmission is due to postsynaptic membrane protonation. Our model will be falsified if cholinergic membranes do not respond to acidification.

Effects of novel triple-stage antimalarial ionic liquids on lipid membrane models

2017 ◽  
Vol 27 (17) ◽  
pp. 4190-4193 ◽  
Author(s):  
Ricardo Ferraz ◽  
Marina Pinheiro ◽  
Ana Gomes ◽  
Cátia Teixeira ◽  
Cristina Prudêncio ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Lipid Membrane ◽  
Membrane Models

scholarly journals Proteins of Excitable Membranes

1969 ◽  
Vol 54 (1) ◽  
pp. 187-224 ◽  
Author(s):  
David Nachmansohn
Keyword(s):  
Electrical Activity ◽  
Essential Role ◽  
Enzyme Inhibitors ◽  
Specific Protein ◽  
Receptor Protein ◽  
Excitable Membranes ◽  
Protein Properties ◽  
Ion Movements ◽  
Hydrolysis Of

Excitable membranes have the special ability of changing rapidly and reversibly their permeability to ions, thereby controlling the ion movements that carry the electric currents propagating nerve impulses. Acetylcholine (ACh) is the specific signal which is released by excitation and is recognized by a specific protein, the ACh-receptor; it induces a conformational change, triggering off a sequence of reactions resulting in increased permeability. The hydrolysis of ACh by ACh-esterase restores the barrier to ions. The enzymes hydrolyzing and forming ACh and the receptor protein are present in the various types of excitable membranes. Properties of the two proteins directly associated with electrical activity, receptor and esterase, will be described in this and subsequent lectures. ACh-esterase has been shown to be located within the excitable membranes. Potent enzyme inhibitors block electrical activity demonstrating the essential role in this function. The enzyme has been recently crystallized and some protein properties will be described. The monocellular electroplax preparation offers a uniquely favorable material for analyzing the properties of the ACh-receptor and its relation to function. The essential role of the receptor in electrical activity has been demonstrated with specific receptor inhibitors. Recent data show the basically similar role of ACh in the axonal and junctional membranes; the differences of electrical events and pharmacological actions are due to variations of shape, structural organization, and environment.

scholarly journals Stability of unimolecular films of 32P-labelled lecithin

1967 ◽  
Vol 105 (1) ◽  
pp. 401-407 ◽  
Author(s):  
H. Hauser ◽  
R. M. C. Dawson
Keyword(s):  
Pressure Change ◽  
Ion Concentration ◽  
Hydrolysis Rate ◽  
Ion Distribution ◽  
Rapid Perfusion ◽  
Poisson Boltzmann ◽  
Rate Of Hydrolysis ◽  
Poisson Boltzmann Equation ◽  
The Stability ◽  
Hydrolysis Of

1. The stability of monolayers of a highly unsaturated yeast lecithin labelled with 32P has been investigated by a surface radioactivity technique. 2. Lecithin films on distilled water at all surface pressures between 6 and 48dynes/cm. were completely stable on rapid perfusion of the subphase and on addition of ionic amphipathic substances to the film. 3. Ultrasonically treated lecithin added to the subphase caused a slow loss of surface radioactivity but little pressure change. 4. The addition of proteins to the subphase caused negligible changes in the film even when conditions were favourable for electrostatic heterocoagulation and penetration. 5. Lecithin films were not hydrolysed by a strongly acid subphase at room temperature. The very low rate of hydrolysis produced by alkali was proportional to the subphase OH−ion concentration: the apparent activation energy and temperature coefficient (Q10) of the reaction were 14250 cal. and 2·37 respectively. 6. Alkaline hydrolysis of lecithin monolayers was markedly stimulated by adding methanol (10–20%, v/v) to the subphase. The addition of ionic amphipaths to the monolayer had the expected type of effect on the hydrolysis rate, but its magnitude was far less than that suggested by an application of the Poisson–Boltzmann equation for ion distribution at a charged interface (Davies & Rideal, 1963).

scholarly journals Permeability Barrier and Microstructure of Skin Lipid Membrane Models of Impaired Glucosylceramide Processing

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Michaela Sochorová ◽  
Klára Staňková ◽  
Petra Pullmannová ◽  
Andrej Kováčik ◽  
Jarmila Zbytovská ◽  
...  
Keyword(s):  
Lipid Membrane ◽  
Permeability Barrier ◽  
Skin Lipid ◽  
Membrane Models

scholarly journals Mimicking the Mammalian Plasma Membrane: An Overview of Lipid Membrane Models for Biophysical Studies

Biomimetics ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 3
Author(s):  
Alessandra Luchini ◽  
Giuseppe Vitiello
Keyword(s):  
Plasma Membrane ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Cell Membranes ◽  
Lipid Membrane ◽  
Lipid Phase ◽  
Chemical Information ◽  
Lipid Species ◽  
Membrane Models ◽  
The Impact

Cell membranes are very complex biological systems including a large variety of lipids and proteins. Therefore, they are difficult to extract and directly investigate with biophysical methods. For many decades, the characterization of simpler biomimetic lipid membranes, which contain only a few lipid species, provided important physico-chemical information on the most abundant lipid species in cell membranes. These studies described physical and chemical properties that are most likely similar to those of real cell membranes. Indeed, biomimetic lipid membranes can be easily prepared in the lab and are compatible with multiple biophysical techniques. Lipid phase transitions, the bilayer structure, the impact of cholesterol on the structure and dynamics of lipid bilayers, and the selective recognition of target lipids by proteins, peptides, and drugs are all examples of the detailed information about cell membranes obtained by the investigation of biomimetic lipid membranes. This review focuses specifically on the advances that were achieved during the last decade in the field of biomimetic lipid membranes mimicking the mammalian plasma membrane. In particular, we provide a description of the most common types of lipid membrane models used for biophysical characterization, i.e., lipid membranes in solution and on surfaces, as well as recent examples of their applications for the investigation of protein-lipid and drug-lipid interactions. Altogether, promising directions for future developments of biomimetic lipid membranes are the further implementation of natural lipid mixtures for the development of more biologically relevant lipid membranes, as well as the development of sample preparation protocols that enable the incorporation of membrane proteins in the biomimetic lipid membranes.

scholarly journals Accumulation of styrene oligomers alters lipid membrane phase order and miscibility

2021 ◽  
Vol 118 (4) ◽  
pp. e2016037118
Author(s):  
Mattia I. Morandi ◽  
Monika Kluzek ◽  
Jean Wolff ◽  
André Schroder ◽  
Fabrice Thalmann ◽  
...  
Keyword(s):  
Phase Behavior ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Spatial Modulation ◽  
Plastic Materials ◽  
Polymeric Species ◽  
Cell Components ◽  
Membrane Models ◽  
Membrane Mechanical Properties

Growth of plastic waste in the natural environment, and in particular in the oceans, has raised the accumulation of polystyrene and other polymeric species in eukyarotic cells to the level of a credible and systemic threat. Oligomers, the smallest products of polymer degradation or incomplete polymerization reactions, are the first species to leach out of macroscopic or nanoscopic plastic materials. However, the fundamental mechanisms of interaction between oligomers and polymers with the different cell components are yet to be elucidated. Simulations performed on lipid bilayers showed changes in membrane mechanical properties induced by polystyrene, but experimental results performed on cell membranes or on cell membrane models are still missing. We focus here on understanding how embedded styrene oligomers affect the phase behavior of model membranes using a combination of scattering, fluorescence, and calorimetric techniques. Our results show that styrene oligomers disrupt the phase behavior of lipid membranes, modifying the thermodynamics of the transition through a spatial modulation of lipid composition.

scholarly journals Phospholipase Cβ1 induces membrane tubulation and is involved in caveolae formation

2016 ◽  
Vol 113 (28) ◽  
pp. 7834-7839 ◽  
Author(s):  
Takehiko Inaba ◽  
Takuma Kishimoto ◽  
Motohide Murate ◽  
Takuya Tajima ◽  
Shota Sakai ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Lipid Membrane ◽  
Membrane Curvature ◽  
Membrane Remodeling ◽  
Ph Domain ◽  
Dynamic Membrane ◽  
C Terminus ◽  
Inositol Phospholipids ◽  
Membrane Tubulation ◽  
Hydrolysis Of

Lipid membrane curvature plays important roles in various physiological phenomena. Curvature-regulated dynamic membrane remodeling is achieved by the interaction between lipids and proteins. So far, several membrane sensing/sculpting proteins, such as Bin/amphiphysin/Rvs (BAR) proteins, are reported, but there remains the possibility of the existence of unidentified membrane-deforming proteins that have not been uncovered by sequence homology. To identify new lipid membrane deformation proteins, we applied liposome-based microscopic screening, using unbiased-darkfield microscopy. Using this method, we identified phospholipase Cβ1 (PLCβ1) as a new candidate. PLCβ1 is well characterized as an enzyme catalyzing the hydrolysis of phosphatidylinositol-4,5-bisphosphate (PIP2). In addition to lipase activity, our results indicate that PLCβ1 possessed the ability of membrane tubulation. Lipase domains and inositol phospholipids binding the pleckstrin homology (PH) domain of PLCβ1 were not involved, but the C-terminal sequence was responsible for this tubulation activity. Computational modeling revealed that the C terminus displays the structural homology to the BAR domains, which is well known as a membrane sensing/sculpting domain. Overexpression of PLCβ1 caused plasma membrane tubulation, whereas knockdown of the protein reduced the number of caveolae and induced the evagination of caveolin-rich membrane domains. Taken together, our results suggest a new function of PLCβ1: plasma membrane remodeling, and in particular, caveolae formation.

scholarly journals Role of lipid packing in the activity of phospholipase C-δ1 as determined by hydrostatic pressure measurements

1999 ◽  
Vol 341 (3) ◽  
pp. 571-576 ◽  
Author(s):  
Mario REBECCHI ◽  
Marjorie BONHOMME ◽  
Suzanne SCARLATA
Keyword(s):  
Hydrostatic Pressure ◽  
Phospholipase C ◽  
Atmospheric Pressure ◽  
Lateral Pressure ◽  
Membrane Surface ◽  
Enzymic Activity ◽  
Lipid Packing ◽  
Multiply Charged ◽  
Hydrolysis Of

Previous studies with phospholipid monolayers revealed a large decrease in the activity of phosphoinositide-specific phospholipase C-δ1 (PLC-δ1) which catalyses the hydrolysis of PtdIns(4,5)P2 as lateral pressure is applied to the membrane. If stress on the membrane is the sole inhibitor of PLC-δ1 activity, the enzyme must penetrate the membrane surface to engage its substrate. To test the effect on PLC-δ1 activity of lipid packing in the absence of a directional stress, we examined the effects of increasing hydrostatic pressure on enzymic activity. We find that, in contrast with monolayer studies, increasing lipid packing by hydrostatic pressure does not affect membrane binding and increases enzymic activity by 90% in going from atmospheric pressure to 108 Pa (approx. 1000 atm). The increase in activity could be accounted for mainly by electrostriction of water around the multiply-charged product. Our results show that when there is no net stress on the monolayer, lipid packing does not alter PLC-δ1 activity, possibly because penetration of the enzyme into the membrane surface is shallow. We suggest that, in biological membranes, the activity of this and possibly other interfacial proteins is independent of headgroup packing.

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