scholarly journals Preferential interactions of primary amine-terminated quantum dots with membrane domain boundaries and lipid rafts revealed with nanometer resolution

2020 ◽  
Vol 7 (1) ◽  
pp. 149-161 ◽  
Author(s):  
Arielle C. Mensch ◽  
Eric S. Melby ◽  
Elizabeth D. Laudadio ◽  
Isabel U. Foreman-Ortiz ◽  
Yongqian Zhang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Lipid Rafts ◽  
Primary Amine ◽  
Membrane Domain ◽  
Intact Cells ◽  
Nanometer Resolution ◽  
Domain Boundaries ◽  
Preferential Interactions ◽  
Liquid Ordered

Primary amine-terminated Qdots preferentially interact with liquid-ordered domain boundaries in bilayers and with lipid rafts in intact cells.

scholarly journals The effect of hydrostatic pressure on model membrane domain composition and lateral compressibility

2016 ◽  
Vol 18 (1) ◽  
pp. 149-155 ◽  
Author(s):  
H. M. G. Barriga ◽  
R. V. Law ◽  
J. M. Seddon ◽  
O. Ces ◽  
N. J. Brooks
Keyword(s):  
Hydrostatic Pressure ◽  
Phase Region ◽  
Model Membrane ◽  
Membrane Domain ◽  
Two Phase ◽  
Domain Composition ◽  
Liquid Ordered ◽  
Diffraction Patterns ◽  
Effect Of Hydrostatic Pressure

We distinguish the liquid ordered and liquid disordered phases in diffraction patterns of biphasic mixtures, comparing their lateral compressibility and report the variations in the two phase region with increasing hydrostatic pressure.

scholarly journals Biomembrane liquid–liquid phase separation and detergent resistance: a relationship strengthened

2009 ◽  
Vol 424 (2) ◽  
pp. e5-e6 ◽  
Author(s):  
David Holowka
Keyword(s):  
Plasma Membrane ◽  
Phase Separation ◽  
Liquid Phase ◽  
Lipid Rafts ◽  
Membrane Vesicles ◽  
Liquid Phase Separation ◽  
Plasma Membrane Vesicles ◽  
Intact Cells ◽  
Acyl Chains ◽  
Liquid Liquid Phase Separation

Since evidence first appeared for ‘detergent-resistant membranes’ in the early to mid-1990s, cell biologists from a wide spectrum of biological sciences have been intrigued by the functional relevance of this indication of membrane heterogeneity, commonly referred to as ‘lipid rafts’. Model membrane studies revealed that these lipid rafts are related to the more ordered liquid phase that forms in a ternary mixture of cholesterol with a phospholipid containing saturated acyl chains and one with unsaturated acyl chains. Giant plasma membrane vesicles that pinch off from cells undergo similar liquid–liquid phase separation as ternary model membranes, and have provided an experimental bridge between these and intact cells. The study by Levental et al. in this issue of the Biochemical Journal provides new insights into the relationship between liquid–liquid phase separation in these plasma membrane vesicles and detergent-resistance of cellular lipid rafts.

scholarly journals Protein sorting by lipid phase-like domains supports emergent signaling function in B lymphocyte plasma membranes

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Matthew B Stone ◽  
Sarah A Shelby ◽  
Marcos F Núñez ◽  
Kathleen Wisser ◽  
Sarah L Veatch
Keyword(s):  
Plasma Membranes ◽  
B Lymphocyte ◽  
Membrane Lipids ◽  
Super Resolution ◽  
Cell Receptor ◽  
Biochemical Networks ◽  
Lipid Phase ◽  
Intact Cells ◽  
Signaling Function ◽  
Liquid Ordered

Diverse cellular signaling events, including B cell receptor (BCR) activation, are hypothesized to be facilitated by domains enriched in specific plasma membrane lipids and proteins that resemble liquid-ordered phase-separated domains in model membranes. This concept remains controversial and lacks direct experimental support in intact cells. Here, we visualize ordered and disordered domains in mouse B lymphoma cell membranes using super-resolution fluorescence localization microscopy, demonstrate that clustered BCR resides within ordered phase-like domains capable of sorting key regulators of BCR activation, and present a minimal, predictive model where clustering receptors leads to their collective activation by stabilizing an extended ordered domain. These results provide evidence for the role of membrane domains in BCR signaling and a plausible mechanism of BCR activation via receptor clustering that could be generalized to other signaling pathways. Overall, these studies demonstrate that lipid mediated forces can bias biochemical networks in ways that broadly impact signal transduction.

scholarly journals Lipid rafts and regulation of the cytoskeleton during T cell activation

2005 ◽  
Vol 360 (1461) ◽  
pp. 1663-1672 ◽  
Author(s):  
Karina F Meiri
Keyword(s):  
T Cell ◽  
Lipid Rafts ◽  
T Cell Activation ◽  
Cell Activation ◽  
Immunological Synapse ◽  
Membrane Lipids ◽  
Actin Dynamics ◽  
Associated Proteins ◽  
Liquid Ordered

The ability of polarized cells to initiate and sustain directional responses to extracellular signals is critically dependent on direct communication between spatially organized signalling modules in the membrane and the underlying cytoskeleton. Pioneering work in T cells has shown that the assembly of signalling modules critically depends on the functional compartmentalization of membrane lipids into ordered microdomains or lipid rafts. The significance of rafts in T cell activation lies not only in their ability to recruit the signalling partners that eventually assemble into a mature immunological synapse but also in their ability to regulate actin dynamics and recruit cytoskeletal associated proteins, thereby achieving the structural polarization underlying stability of the synapse—a critical prerequisite for activation to be sustained. Lipid rafts vary quite considerably in size and visualizing the smallest of them in vivo has been challenging. Nonetheless it is now been shown quite convincingly that a surprisingly large proportion—in the order of 50%—of external membrane lipids (chiefly cholesterol and glycosphingolipids) can be dynamically localized in these liquid ordered rafts. Complementary inner leaflet rafts are less well characterized, but contain phosphoinositides as an important functional component that is crucial for regulating the behaviour of the actin cytoskeleton. This paper provides an overview of the interdependency between signalling and cytoskeletal polarization, and in particular considers how regulation of the cytoskeleton plays a crucial role in the consolidation of rafts and their stabilization into the immunological synapse.

Characterization of Primary Amine Capped CdSe, ZnSe, and ZnS Quantum Dots by FT-IR: Determination of Surface Bonding Interaction and Identification of Selective Desorption

Langmuir ◽  
2011 ◽  
Vol 27 (13) ◽  
pp. 8486-8493 ◽  
Author(s):  
Jason K. Cooper ◽  
Alexandra M. Franco ◽  
Sheraz Gul ◽  
Carley Corrado ◽  
Jin Z. Zhang
Keyword(s):  
Quantum Dots ◽  
Primary Amine ◽  
Bonding Interaction ◽  
Ft Ir ◽  
Surface Bonding

scholarly journals Dietary fish oil and DHA down-regulate antigen-activated CD4+T-cells while promoting the formation of liquid-ordered mesodomains

2013 ◽  
Vol 111 (2) ◽  
pp. 254-260 ◽  
Author(s):  
Wooki Kim ◽  
Rola Barhoumi ◽  
David N. McMurray ◽  
Robert S. Chapkin
Keyword(s):  
T Cells ◽  
T Cell ◽  
Transgenic Mice ◽  
Fish Oil ◽  
Lipid Rafts ◽  
T Cell Activation ◽  
Cell Function ◽  
Immunological Synapse ◽  
Potential Contribution ◽  
Liquid Ordered

We have demonstrated previously thatn-3 PUFA endogenously produced byfat-1transgenic mice regulate CD4+T-cell function by affecting the formation of lipid rafts, liquid-ordered mesodomains in the plasma membrane. In the present study, we tested the effects of dietary sources ofn-3 PUFA, i.e. fish oil (FO) or purified DHA, when compared with ann-6 PUFA-enriched maize oil control diet in DO11.10 T-cell receptor transgenic mice. Dietaryn-3 PUFA were enriched in CD4+T-cells, resulting in the increase of then-3:n-6 ratio. Following antigen-specific CD4+T-cell activation by B-lymphoma cells pulsed with the ovalbumin 323–339 peptide, the formation of liquid-ordered mesodomains at the immunological synapse relative to the whole CD4+T-cell, as assessed by Laurdan labelling, was increased (P< 0·05) in the FO-fed group. The FO diet also suppressed (P< 0·05) the co-localisation of PKCθ with ganglioside GM1 (monosialotetrahexosylganglioside), a marker for lipid rafts, which is consistent with previous observations. In contrast, the DHA diet down-regulated (P< 0·05) PKCθ signalling by moderately affecting the membrane liquid order at the immunological synapse, suggesting the potential contribution of the other majorn-3 PUFA components of FO, including EPA.

scholarly journals Evaluation of the membrane-spanning domain of ClC-2

2006 ◽  
Vol 396 (3) ◽  
pp. 449-460 ◽  
Author(s):  
Mohabir Ramjeesingh ◽  
Canhui Li ◽  
Yi-Min She ◽  
Christine E. Bear
Keyword(s):  
Chloride Channels ◽  
Molecular Mechanisms ◽  
Protein Structures ◽  
Idiopathic Epilepsy ◽  
Membrane Domains ◽  
Membrane Domain ◽  
Domain Boundaries ◽  
Thiol Reagent ◽  
Membrane Spanning ◽  
Prokaryotic Protein

The ClC family of chloride channels and transporters includes several members in which mutations have been associated with human disease. An understanding of the structure–function relationships of these proteins is essential for defining the molecular mechanisms underlying pathogenesis. To date, the X-ray crystal structures of prokaryotic ClC transporter proteins have been used to model the membrane domains of eukaryotic ClC channel-forming proteins. Clearly, the fidelity of these models must be evaluated empirically. In the present study, biochemical tools were used to define the membrane domain boundaries of the eukaryotic protein, ClC-2, a chloride channel mutated in cases of idiopathic epilepsy. The membrane domain boundaries of purified ClC-2 and accessible cysteine residues were determined after its functional reconstitution into proteoliposomes, labelling using a thiol reagent and proteolytic digestion. Subsequently, the lipid-embedded and soluble fragments generated by trypsin-mediated proteolysis were studied by MS and coverage of approx. 71% of the full-length protein was determined. Analysis of these results revealed that the membrane-delimited boundaries of the N- and C-termini of ClC-2 and the position of several extramembrane loops determined by these methods are largely similar to those predicted on the basis of the prokaryotic protein [ecClC (Escherichia coli ClC)] structures. These studies provide direct biochemical evidence supporting the relevance of the prokaryotic ClC protein structures towards understanding the structure of mammalian ClC channel-forming proteins.

Sign in / Sign up

Export Citation Format

Share Document