Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2024.11.04.622000

Shapes of Plasma Membrane Vesicles and PC-Cholesterol Vesicles Reveal Their Effective Spontaneous Curvature

Kaur, H.·Pandey, T.·BHATIA, T.
View original source ↗Export metadata ↓

Abstract

Giant membrane vesicles (GUVs) and giant plasma membrane vesicles (GPMVs) are useful models for studying cellular membrane properties. Our research analyzed the reduced volume of vesicles made from phospholipid and 10% cholesterol to investigate transbilayer sugar asymmetries. We found that GPMVs have an average reduced volume of (0.88 {+/-} 0.06) with buffer asymmetry of 323 mM, lower than the (0.92 {+/-} 0.08) observed for DOPC: cholesterol vesicles with sucrose/glucose asymmetry of 390 mM. GUVs with different sugars inside and outside were more deflated, demonstrating a greater volume reduction than those with the same sugar inside and out. We applied the area-difference elasticity (ADE) model to map GPMVs and used the spontaneous curvature (SC) model to analyze DOPC: cholesterol GUVs, extracting spontaneous curvature based on their reduced volume. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=178 SRC="FIGDIR/small/622000v1_ufig1.gif" ALT="Figure 1"> View larger version (63K): org.highwire.dtl.DTLVardef@178828forg.highwire.dtl.DTLVardef@c38f8eorg.highwire.dtl.DTLVardef@105c783org.highwire.dtl.DTLVardef@6da36d_HPS_FORMAT_FIGEXP M_FIG C_FIG

Explore related subjects

biophysicsPreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Kaur, H., Pandey, T., BHATIA, T.. 2024-11-06. Shapes of Plasma Membrane Vesicles and PC-Cholesterol Vesicles Reveal Their Effective Spontaneous Curvature. https://doi.org/10.1101/2024.11.04.622000

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Mechanism of molecular recognition revealed through dynamic drug binding pathways to SARS-CoV-2 main protease

Characterization of drug-binding pathways remains experimentally limited by transient intermediates and computationally challenging due to long timescales intractable for conventional molecular dynamics. To address these challenges, we combined solution NMR titrations with weighted ensemble (WE) enhanced sampling simulations to resolve atomistic pathways of nirmatrelvir binding to the SARS-CoV-2 main protease. NMR titration revealed residue-dependent heterogeneity spanning fast, intermediate, and slow exchange regimes. WE simulations complement the NMR by providing insights into unassigned residues and adding time-resolved and three-dimensional structural context. We map key interactions along two distinct binding pathways, provide dynamic explanations for residues involved in resistance, and capture unique backbone conformations compared to those sampled in unbound or bound states. Our comprehensive binding model is consistent with a combined conformational selection and induced fit mechanism in which early transient contacts are made with residues E47 and L50 and allosteric motions are centered around residue V204 of the distal domain. This synergistic application of WE and titration NMR enables a more comprehensive characterization of drug binding than either method alone, providing an integrated framework that may have broader applicability to defining structure-kinetic relationships and guiding design of next-generation inhibitors.

biophysics↗
bioRxiv2026

Fibers and Glasses are Competing Material States in FUS Protein Condensation

Dense, well-ordered material states of proteins form the amyloid fibers that are a hallmark of neurodegenerative disease in the brain. Beyond forming amyloid fibers, some of these proteins can also adopt other material states termed condensates which are initially liquid-like but evolve to a soft, glassy phase. Fiber growth requires a large supply of monomers and, thus, it is often speculated that fibers emerge from within a dense condensate as it ages and its microscopic dynamics slow into a glassy state. Here, we use the well-established model system Fused in Sarcoma (FUS) to directly observe, quantify and theoretically describe fiber growth and its interplay with condensates. We report the discovery that fibers grow overwhelmingly in the dilute phase surrounding the condensates while the condensates concurrently evolve to a glassy arrested solid. The resulting protein fibers and glassy condensates are both distinct solid-like phases that coexist but do not directly interconvert. Taken together, these findings reveal that there are two competitive aging pathways in FUS condensation that are linked through phase separation kinetics.

biophysics↗
bioRxiv2026

A Minimally Perturbative DARPin Probe for Quantitative Fluorescence Imaging of the Human TCR-CD3 Complex

Fluorescence microscopy is a powerful tool for dissecting the molecular mechanisms of T-cell antigen recognition in living cells, but its quantitative insight critically depends on non-perturbative, high-quality probes. Here, we repurpose a small (~15 kDa) CD3epsilon-binding DARPin (designed ankyrin repeat proteins) to a fluorescent label for T-cell receptor (TCR)/CD3 complexes on primary human CD8+ T-cells, with the aim of generating a powerful tool for quantitative analysis, single-molecule tracking, and advanced imaging of TCR dynamics. We show that the DARPin binds CD3{varepsilon} with high affinity and selectivity and using single molecule tracking and brightness analysis, we characterize the TCR-CD3 diffusion behavior and show that the DARPin binds to both CD3epsilon; subunits. Importantly, labeling preserves antigen sensitivity: on supported lipid bilayers presenting cognate pMHC, T-cells remain responsive, assemble synapses, form TCR microclusters, and initiate signaling similar to unlabeled controls. We further demonstrate compatibility with lattice light-sheet microscopy for volumetric imaging of T-cell - APC interactions in living cells. Together, these results establish DARPins as versatile, minimally perturbative probes for high resolution, quantitative studies of T cell synapse organization and signaling.

biophysics↗