Control of the postsynaptic membrane viscosity
Journal of Neuroscience. 2009-03-04; 29(9): 2926-2937
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1. J Neurosci. 2009 Mar 4;29(9):2926-37. doi: 10.1523/JNEUROSCI.4445-08.2009.
Control of the postsynaptic membrane viscosity.
Renner M(1), Choquet D, Triller A.
(1)Institut National de la Santé et de la Recherche Médicale, Biologie Cellulaire
de la Synapse, 75005 Paris, France.
The physical properties of the postsynaptic membrane (PSM), including its
viscosity, determine its capacity to regulate the net flux of synaptic membrane
proteins such as neurotransmitter receptors. To address these properties, we
studied the lateral diffusion of glycophosphatidylinositol-anchored green
fluorescent protein and cholera toxin bound to the external leaflet of the plasma
membrane. Relative to extrasynaptic regions, their mobility was reduced at
synapses and even more at inhibitory than at excitatory ones. This indicates a
higher density of obstacles and/or higher membrane viscosity at inhibitory
contacts. Actin depolymerization reduced the confinement and accelerated a
population of fast, mobile molecules. The compaction of obstacles thus depends on
actin cytoskeleton integrity. Cholesterol depletion increased the mobility of the
slow diffusing molecules, allowing them to diffuse more rapidly through the
crowded PSM. Thus, the PSM has lipid-raft properties, and the density of
obstacles to diffusion depends on filamentous actin. Therefore, lipid composition
and actin-dependent protein compaction regulate viscosity of the PSM and,
consequently, the molecular flow in and out of synapses.
PMID: 19261888 [Indexed for MEDLINE]