The impact of physiological crowding on the diffusivity of membrane bound proteins

Houser, Justin R.; Busch, David J.; Bell, David R.; Li, Brian; Ren, Pengyu; Stachowiak, Jeanne C.

doi:10.1039/c5sm02572a

Cited by 36 publications

(43 citation statements)

References 26 publications

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“…Diffusion of all tested molecules was significantly faster in GPMVs than in living cells but still significantly slower than in the GUVs ( Figure 2D). We account these differences due to the missing hindrance from the actin cytoskeleton in GPMVs (also suggested by previous measurements ) and less molecular crowding in GUVs (Houser et al, 2016), respectively. All tested molecules diffused with similar diffusion coefficients in GUVs (D ≈ 8.5 µm 2 /s).…”

Section: Diffusion In Gpmvs Is Faster Than In Cells But Slower Than mentioning

confidence: 73%

Diffusion of lipids and GPI-anchored proteins in actin-free plasma membrane vesicles measured by STED-FCS

Schneider

Clausen

Waithe

et al. 2016

Preprint

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Diffusion and interaction dynamics of molecules at the plasma membrane play an important role in cellular signalling. These have been suggested to be strongly associated with the actin cytoskeleton. Here, we utilise super-resolution STED microscopy combined with fluorescence correlation spectroscopy (STED-FCS) to access the sub-diffraction diffusion regime of different fluorescent lipid analogues and GPI-anchored proteins (GPI-APs) in the cellular plasma membrane, and compare it to the diffusion regime of these molecules in cell-derived actin-free giant plasma membrane vesicles (GPMVs). We show that phospholipids and sphingomyelin, which undergo hindered diffusion in the live cell membrane, diffuse freely in the GPMVs. In contrast to sphingomyelin, which is transiently trapped on molecular-scale complexes in intact cells, diffusion of the ganglioside lipid GM1 suggests transient incorporation into nanodomains, which is less influenced by the actin cortex. Finally, our data on GPI-APs indicate two molecular pools in living cells, one pool showing high mobility with trapped and compartmentalized diffusion, and the other forming immobile clusters both of which disappear in GPMVs. Our data underlines the crucial role of the actin cortex in maintaining hindered diffusion modes of most but not all membrane molecules.

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Section: Diffusion In Gpmvs Is Faster Than In Cells But Slower Than mentioning

confidence: 73%

Diffusion of lipids and GPI-anchored proteins in actin-free plasma membrane vesicles measured by STED-FCS

Schneider

Clausen

Waithe

et al. 2016

Preprint

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“…However, few studies have ventured a comprehensive comparison of their biophysical properties as a function of the inherent parameters (a support presence, its material, model geometry etc.) 18,25,28,[40][41][42][43] . Indeed, a few studies have highlighted this concern by demonstrating altered protein functionality in different membrane models 44,45 .…”

Section: Discussionmentioning

confidence: 99%

Impact of nanoscale hindrances on the relationship between lipid packing and diffusion in model membranes

Beckers

Urbančič

Sezgin

2020

Preprint

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Membrane models have allowed for precise study of the plasma membrane's biophysical properties, helping to unravel both structural and dynamic motifs within cell biology. Free standing and supported bilayer systems are popular models to reconstitute the membrane related processes. Although it is well-known that each have their advantages and limitations, comprehensive comparison of their biophysical properties is still lacking. Here, we compare the diffusion and lipid packing in giant unilamellar vesicles, planar and spherical supported membranes and cell-derived giant plasma membrane vesicles. We apply florescence correlation spectroscopy, spectral imaging and super-resolution STED-FCS to study the diffusivity, lipid packing and nanoscale architecture of these membrane systems, respectively.Our data show that lipid packing and diffusivity is tightly correlated in free-standing bilayers.However, nanoscale interactions in the supported bilayers cause deviation from this correlation.This data is essential to develop accurate theoretical models of the plasma membrane and will serve as a guideline for suitable model selection in future studies to reconstitute biological processes.

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“…For example, curved lipids and curvature-sensing proteins could be recruited to newly curved membrane areas (66), aggregation of glycoproteins could cocluster lectins that bind the glycans in the glycocalyx (67), and membrane invagination and endocytosis rates could be affected by membrane curvature (68). Physiological crowding by the glycocalyx is known to hinder membrane protein diffusion (69). Clustering of the glycocalyx constituents because of external forces could also create alternating regions of low and high diffusivities for other membrane-bound proteins.…”

Section: Membrane Shape and Molecular Organization And Transportmentioning

confidence: 99%

Equilibrium Modeling of the Mechanics and Structure of the Cancer Glycocalyx

Gandhi

Koch

Paszek

2019

Biophysical Journal

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The glycocalyx is a thick coat of proteins and carbohydrates on the outer surface of all eukaryotic cells. Overproduction of large, flexible or rod-like biopolymers, including hyaluronic acid and mucins, in the glycocalyx strongly correlates with the aggression of many cancer types. However, theoretical frameworks to predict the effects of these changes on cancer cell adhesion and other biophysical processes remain limited. Here, we propose a detailed modeling framework for the glycocalyx incorporating important physical effects of biopolymer flexibility, excluded volume, counterion mobility, and coupled membrane deformations. Because mucin and hyaluronic biopolymers are proposed to extend and rigidify depending on the extent of their decoration with side chains, we propose and consider two limiting cases for the structural elements of the glycocalyx: stiff beams and flexible chains. Simulations predict the mechanical response of the glycocalyx to compressive loads, which are imposed on cells residing in the highly confined spaces of the solid tumor or invaded tissues. Notably, the shape of the mechanical response transitions from hyperbolic to sigmoidal for more rod-like glycocalyx elements. These mechanical responses, along with the corresponding equilibrium protein organizations and membrane topographies, are summarized to aid in hypothesis generation and the evaluation of future experimental measurements. Overall, the modeling framework developed provides a theoretical basis for understanding the physical biology of the glycocalyx in human health.

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The impact of physiological crowding on the diffusivity of membrane bound proteins

Cited by 36 publications

References 26 publications

Diffusion of lipids and GPI-anchored proteins in actin-free plasma membrane vesicles measured by STED-FCS

Diffusion of lipids and GPI-anchored proteins in actin-free plasma membrane vesicles measured by STED-FCS

Impact of nanoscale hindrances on the relationship between lipid packing and diffusion in model membranes

Equilibrium Modeling of the Mechanics and Structure of the Cancer Glycocalyx

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