dorsal/arxiv
View SchemaStructural Transition of Actin Filament in a Cell-Sized Water Droplet with a Phospholipid Membrane
| Authors | M. Hase, K. Yoshikawa |
|---|---|
| Categories | |
| ArXiv ID | physics/0510220 |
| URL | https://arxiv.org/abs/physics/0510220 |
| DOI | 10.1063/1.2174004 |
Abstract
Actin filament, F-actin, is a semiflexible polymer with a negative charge, and is one of the main constituents on cell membranes. To clarify the effect of cross-talk between a phospholipid membrane and actin filaments in cells, we conducted microscopic observations on the structural changes in actin filaments in a cell-sized (several tens of micrometers in diameter) water droplet coated with a phospholipid membrane such as phosphatidylserine (PS; negatively-charged head group) or phosphatidylethanolamine (PE; neutral head group) as a simple model of a living cell membrane. With PS, actin filaments are distributed uniformly in the water phase without adsorption onto the membrane surface between 2 and 6 mM Mg2+, while between 6 and 12 mM Mg2+, actin filaments are adsorbed onto the inner membrane surface. With PE, actin filaments are uniformly adsorbed onto the inner membrane surface between 2 and 12 mM Mg2+. With both PS and PE membranes, at Mg2+ concentrations higher than 12 mM, thick bundles are formed in the bulk water droplet accompanied by the dissolution of actin filaments from the membrane surface. The attraction between actin filaments and membrane is attributable to an increase in the translational entropy of counterions accompanied by the adsorption of actin filaments onto the membrane surface. These results suggest that a microscopic water droplet coated with phospholipid can serve as an easy-to-handle model of cell membranes.
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"abstract": "Actin filament, F-actin, is a semiflexible polymer with a negative charge,\nand is one of the main constituents on cell membranes. To clarify the effect of\ncross-talk between a phospholipid membrane and actin filaments in cells, we\nconducted microscopic observations on the structural changes in actin filaments\nin a cell-sized (several tens of micrometers in diameter) water droplet coated\nwith a phospholipid membrane such as phosphatidylserine (PS; negatively-charged\nhead group) or phosphatidylethanolamine (PE; neutral head group) as a simple\nmodel of a living cell membrane. With PS, actin filaments are distributed\nuniformly in the water phase without adsorption onto the membrane surface\nbetween 2 and 6 mM Mg2+, while between 6 and 12 mM Mg2+, actin filaments are\nadsorbed onto the inner membrane surface. With PE, actin filaments are\nuniformly adsorbed onto the inner membrane surface between 2 and 12 mM Mg2+.\nWith both PS and PE membranes, at Mg2+ concentrations higher than 12 mM, thick\nbundles are formed in the bulk water droplet accompanied by the dissolution of\nactin filaments from the membrane surface. The attraction between actin\nfilaments and membrane is attributable to an increase in the translational\nentropy of counterions accompanied by the adsorption of actin filaments onto\nthe membrane surface. These results suggest that a microscopic water droplet\ncoated with phospholipid can serve as an easy-to-handle model of cell\nmembranes.",
"arxiv_id": "physics/0510220",
"authors": [
"M. Hase",
"K. Yoshikawa"
],
"categories": [
"physics.chem-ph"
],
"doi": "10.1063/1.2174004",
"title": "Structural Transition of Actin Filament in a Cell-Sized Water Droplet with a Phospholipid Membrane",
"url": "https://arxiv.org/abs/physics/0510220"
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