scholarly journals Cholesterol and anionic phospholipids increase the binding of amyloidogenic transthyretin to lipid membranes

2008 ◽  
Vol 1778 (1) ◽  
pp. 198-205 ◽  
Author(s):  
Xu Hou ◽  
Adam Mechler ◽  
Lisandra L. Martin ◽  
Marie-Isabel Aguilar ◽  
David H. Small
Keyword(s):  
Lipid Membranes ◽  
Anionic Phospholipids

scholarly journals Molecular mechanism for kinesin-1 direct membrane recognition

2021 ◽  
Author(s):  
Zuriñe Antón ◽  
Johannes F. Weijman ◽  
Christopher Williams ◽  
Edmund R.R. Moody ◽  
Judith Mantell ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Cell Biology ◽  
Phylogenetic Analyses ◽  
Adaptor Proteins ◽  
Coincidence Detection ◽  
Organelle Transport ◽  
Splice Isoforms ◽  
Anionic Phospholipids ◽  
Direct Binding ◽  
Carboxy Terminal

AbstractThe cargo-binding capabilities of cytoskeletal motor proteins have expanded during evolution through both gene duplication and alternative splicing. For the light chains of the kinesin-1 family of microtubule motors, this has resulted in an array of carboxy-terminal domain sequences of unknown molecular function. Here, combining phylogenetic analyses with biophysical, biochemical and cell biology approaches we identify a highly conserved membrane-induced curvature-sensitive amphipathic helix within this region of a newly defined subset of long kinesin light chain paralogues and splice isoforms. This helix mediates the direct binding of kinesin-1 to lipid membranes. Membrane binding requires specific anionic phospholipids and is important for kinesin-1 dependent lysosome positioning, a canonical activity that until now has been attributed exclusively the recognition of organelle-associated cargo adaptor proteins. This leads us to propose a new protein-lipid coincidence detection framework for kinesin-1 mediated organelle transport.

scholarly journals Molecular mechanism for kinesin-1 direct membrane recognition

2021 ◽  
Vol 7 (31) ◽  
pp. eabg6636
Author(s):  
Zuriñe Antón ◽  
Johannes F. Weijman ◽  
Christopher Williams ◽  
Edmund R. R. Moody ◽  
Judith Mantell ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
Cell Biology ◽  
Phylogenetic Analyses ◽  
Adaptor Proteins ◽  
Coincidence Detection ◽  
Organelle Transport ◽  
Splice Isoforms ◽  
Anionic Phospholipids ◽  
Direct Binding ◽  
Membrane Recognition

The cargo-binding capabilities of cytoskeletal motor proteins have expanded during evolution through both gene duplication and alternative splicing. For the light chains of the kinesin-1 family of microtubule motors, this has resulted in an array of carboxyl-terminal domain sequences of unknown molecular function. Here, combining phylogenetic analyses with biophysical, biochemical, and cell biology approaches, we identify a highly conserved membrane-induced curvature-sensitive amphipathic helix within this region of a subset of long kinesin light-chain paralogs and splice isoforms. This helix mediates the direct binding of kinesin-1 to lipid membranes. Membrane binding requires specific anionic phospholipids, and it contributes to kinesin-1–dependent lysosome positioning, a canonical activity that, until now, has been attributed exclusively the recognition of organelle-associated cargo adaptor proteins. This leads us to propose a protein-lipid coincidence detection framework for kinesin-1–mediated organelle transport.

Redox Reactions in Lipid Membranes as a Model for Primordial Energy-Conserving Systems

1997 ◽  
Vol 161 ◽  
pp. 437-442
Author(s):  
Salvatore Di Bernardo ◽  
Romana Fato ◽  
Giorgio Lenaz
Keyword(s):  
Experimental Evidence ◽  
Lipid Membranes ◽  
Energy Supply ◽  
Redox Reactions ◽  
Living Systems ◽  
Asymmetric Distribution ◽  
Conservation Of Energy ◽  
Asymmetrical Distribution ◽  
Energy Conserving ◽  
Living Organisms

AbstractOne of the peculiar aspects of living systems is the production and conservation of energy. This aspect is provided by specialized organelles, such as the mitochondria and chloroplasts, in developed living organisms. In primordial systems lacking specialized enzymatic complexes the energy supply was probably bound to the generation and maintenance of an asymmetric distribution of charged molecules in compartmentalized systems. On the basis of experimental evidence, we suggest that lipophilic quinones were involved in the generation of this asymmetrical distribution of charges through vectorial redox reactions across lipid membranes.

Observation of Concanavalin-A receptors on hydrated planar erythrocyte membrane film by in situ electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 608-609
Author(s):  
Neng-Bo He ◽  
S.W. Hui
Keyword(s):  
Lipid Bilayers ◽  
Erythrocyte Membrane ◽  
Lipid Membranes ◽  
Surface Film ◽  
Biological Membranes ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Black Lipid Membranes ◽  
Fine Mesh ◽  
Planar Films

Monolayers and planar "black" lipid membranes have been widely used as models for studying the structure and properties of biological membranes. Because of the lack of a suitable method to prepare these membranes for electron microscopic observation, their ultrastructure is so far not well understood. A method of forming molecular bilayers over the holes of fine mesh grids was developed by Hui et al. to study hydrated and unsupported lipid bilayers by electron diffraction, and to image phase separated domains by diffraction contrast. We now adapted the method of Pattus et al. of spreading biological membranes vesicles on the air-water interfaces to reconstitute biological membranes into unsupported planar films for electron microscopic study. hemoglobin-free human erythrocyte membrane stroma was prepared by hemolysis. The membranes were spreaded at 20°C on balanced salt solution in a Langmuir trough until a surface pressure of 20 dyne/cm was reached. The surface film was repeatedly washed by passing to adjacent troughs over shallow partitions (fig. 1).

Direct visualization of phase-separated domains in lipid membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 290-291
Author(s):  
S. W. Hui ◽  
T. P. Stewart
Keyword(s):  
Lipid Membranes ◽  
Structural Information ◽  
Freeze Fracture ◽  
Biological Molecules ◽  
Vacuum Drying ◽  
Direct Visualization ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Hydrocarbon Chains

Direct electron microscopic study of biological molecules has been hampered by such factors as radiation damage, lack of contrast and vacuum drying. In certain cases, however, the difficulties may be overcome by using redundent structural information from repeating units and by various specimen preservation methods. With bilayers of phospholipids in which both the solid and fluid phases co-exist, the ordering of the hydrocarbon chains may be utilized to form diffraction contrast images. Domains of different molecular packings may be recgnizable by placing properly chosen filters in the diffraction plane. These domains would correspond to those observed by freeze fracture, if certain distinctive undulating patterns are associated with certain molecular packing, as suggested by X-ray diffraction studies. By using an environmental stage, we were able to directly observe these domains in bilayers of mixed phospholipids at various temperatures at which their phases change from misible to inmissible states.

A Novel Reconstitution Method for Inducing the Formation of Regular 2-Dimensional Arrays of Membrane Proteins and Lipids

1988 ◽  
Vol 46 ◽  
pp. 152-153 ◽  
Author(s):  
A. Engel ◽  
A. Holzenburg ◽  
K. Stauffer ◽  
J. Rosenbusch ◽  
U. Aebi
Keyword(s):  
Membrane Proteins ◽  
Flow Rate ◽  
Lipid Membranes ◽  
Functional Characterization ◽  
Dimensional Structure ◽  
Electron Crystallography ◽  
Peltier Element ◽  
Protein Ratio ◽  
Precise Control ◽  
3 Dimensional

Reconstitution of solubilized and purified membrane proteins in the presence of phospholipids into vesicles allows their functions to be studied by simple bulk measurements (e.g. diffusion of differently sized solutes) or by conductance measurements after transformation into planar membranes. On the other hand, reconstitution into regular protein-lipid arrays, usually forming at a specific lipid-to-protein ratio, provides the basis for determining the 3-dimensional structure of membrane proteins employing the tools of electron crystallography.To refine reconstitution conditions for reproducibly inducing formation of large and highly ordered protein-lipid membranes that are suitable for both electron crystallography and patch clamping experiments aimed at their functional characterization, we built a flow-dialysis device that allows precise control of temperature and flow-rate (Fig. 1). The flow rate is generated by a peristaltic pump and can be adjusted from 1 to 500 ml/h. The dialysis buffer is brought to a preselected temperature during its travel through a meandering path before it enters the dialysis reservoir. A Z-80 based computer controls a Peltier element allowing the temperature profile to be programmed as function of time.

What do nanometer molecular trajectories tell us about heterogeneous cell surface domaines?

1995 ◽  
Vol 53 ◽  
pp. 786-787
Author(s):  
Watt W. Webb
Keyword(s):  
Cell Surface ◽  
Lipid Membranes ◽  
Surface Proteins ◽  
Protein Diffusion ◽  
Coated Pits ◽  
Cell Surface Proteins ◽  
Membrane Heterogeneity ◽  
Fluorescence Photobleaching Recovery ◽  
Photobleaching Recovery ◽  
Plasma Membrane Heterogeneity

Plasma membrane heterogeneity is implicit in the existence of specialized cell surface organelles which are necessary for cellular function; coated pits, post and pre-synaptic terminals, microvillae, caveolae, tight junctions, focal contacts and endothelial polarization are examples. The persistence of these discrete molecular aggregates depends on localized restraint of the constituent molecules within specific domaines in the cell surface by strong intermolecular bonds and/or anchorage to extended cytoskeleton. The observed plasticity of many of organelles and the dynamical modulation of domaines induced by cellular signaling evidence evanescent intermolecular interactions even in conspicuous aggregates. There is also strong evidence that universal restraints on the mobility of cell surface proteins persist virtually everywhere in cell surfaces, not only in the discrete organelles. Diffusion of cell surface proteins is slowed by several orders of magnitude relative to corresponding protein diffusion coefficients in isolated lipid membranes as has been determined by various ensemble average methods of measurement such as fluorescence photobleaching recovery(FPR).

Thrombin Generation Measured Ex Vivo Following Microvasculor Injury Is Increased in SLE Patients with Antiphospholipid-protein Antibodies

1997 ◽  
Vol 78 (04) ◽  
pp. 1173-1177 ◽  
Author(s):  
Jacek Musiał ◽  
Jakub Swadźba ◽  
Miłosz Jankowski ◽  
Marek Grzywacz ◽  
Stanisława Bazan-Socha ◽  
...  
Keyword(s):  
Lupus Erythematosus ◽  
Thrombin Generation ◽  
Ex Vivo ◽  
Skin Incision ◽  
Anticardiolipin Antibodies ◽  
Small Blood Vessel ◽  
Anionic Phospholipids ◽  
Increased Risk ◽  
High Concentrations

SummaryAntiphospholipid-protein antibodies (APA) include lupus-type anticoagulant (LA) and antibodies recognizing complexes of anionic phospholipids (e.g. cardiolipin) and proteins (e.g. prothrombin and (β2-glycoprotein I). The presence of APA is associated with an increased risk of both arterial and venous thrombosis. However, the pathogenic mechanism leading to thrombosis in patients with APA remains unclear. We studied 32 patients with systemic lupus erythematosus (SLE) who were divided into two groups depending on the presence (n = 19) or absence (n = 13) of APA. Healthy volunteers (n = 12) matched by age and sex served as controls. In all subjects LA and IgG class anticardiolipin antibodies (ACA) were determined. Thrombin generation was monitored ex vivo measuring fibrinopeptide A (FPA) and prothrombin fragment F1 + 2 (F1 + 2) in blood emerging from a skin microvasculature injury, collected at 30 second intervals. In subjects with antiphospholipid antibodies mean FPA and F1 + 2 concentrations were signiF1cantly higher at most blood sampling times than in controls. In some SLE patients with APA the process of thrombin generation was clearly disturbed and very high concentrations of F1brinopeptide A were detected already in the F1rst samples collected. Two minutes after skin incision SLE patients without APA produced slightly more FPA, but not F1 + 2, as compared to healthy subjects. Mathematical model applied to analyze the thrombin generation kinetics revealed that APA patients generated signiF1cantly greater amounts of thrombin than healthy controls (p = 0.02 for either marker). In contrast, in the same patients generation of thrombin in recalciF1ed plasma in vitro was delayed pointing to the role of endothelium in the phenomenon studied. In summary, these data show for the F1rst time that in SLE patients with antiphospholipid-protein antibodies thrombin generation after small blood vessel injury is markedly increased. Enhanced thrombin generation might explain thrombotic tendency observed in these patients.

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