Recent Experiments Support a Microemulsion Origin of Plasma Membrane Domains: Dependence of Domain Size on Physical Parameters
1
Department of Physics, University of Washington, Seattle, WA 98195, USA
2
Department of Physics, Kent State University, Kent, OH 44242, USA
*
Author to whom correspondence should be addressed.
Membranes 2020, 10(8), 167; https://doi.org/10.3390/membranes10080167
Received: 2 July 2020 / Revised: 21 July 2020 / Accepted: 24 July 2020 / Published: 28 July 2020
(This article belongs to the Special Issue Dynamics and Nano-Organization in Plasma Membranes)
It is widely, but not universally, believed that the lipids of the plasma membrane are not uniformly distributed, but that “rafts” of sphingolipids and cholesterol float in a “sea” of unsaturated lipids. The physical origin of such heterogeneities is often attributed to a phase coexistence between the two different domains. We argue that this explanation is untenable for several reasons. Further, we note that the results of recent experiments are inconsistent with this picture. However, they are quite consistent with an alternate explanation, namely, that the plasma membrane is a microemulsion of the two kinds of regions. To show this, we briefly review a simplified version of this theory and its phase diagram. We also explicate the dependence of the predicted domain size on four physical parameters. They are the energy cost of gradients in the composition, the spontaneous curvature of the membrane, its bending modulus and its surface tension. Taking values of the latter two from experiment, we obtain domain sizes for several different cell types that vary from 58 to 88 nm.
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Keywords:
plasma membrane; rafts; microemulsion; phase-separation; domain size
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MDPI and ACS Style
Allender, D.W.; Schick, M. Recent Experiments Support a Microemulsion Origin of Plasma Membrane Domains: Dependence of Domain Size on Physical Parameters. Membranes 2020, 10, 167. https://doi.org/10.3390/membranes10080167
AMA Style
Allender DW, Schick M. Recent Experiments Support a Microemulsion Origin of Plasma Membrane Domains: Dependence of Domain Size on Physical Parameters. Membranes. 2020; 10(8):167. https://doi.org/10.3390/membranes10080167
Chicago/Turabian StyleAllender, David W.; Schick, M. 2020. "Recent Experiments Support a Microemulsion Origin of Plasma Membrane Domains: Dependence of Domain Size on Physical Parameters" Membranes 10, no. 8: 167. https://doi.org/10.3390/membranes10080167
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