The excitatory postsynaptic density is a size exclusion diffusion environment.
Receptors are concentrated in the postsynaptic membrane but can enter and exit synapses rapidly during both basal turnover and processes of synaptic plasticity. How the exchange of receptors by lateral diffusion between synaptic and extrasynaptic areas is regulated remains largely unknown. We investigated the structural properties of the postsynaptic membrane that allow these movements by addressing the diffusion behaviors of AMPA receptors (AMPARs) and different lipids. Using single molecule tracking we found that not only AMPARs but also lipids, which are not synaptically enriched, display confined diffusion at synapses. Each molecule type displays a different average confinement area, smaller molecules being confined to smaller areas. Glutamate application increases the mobility of all molecules. The structure of the synaptic membrane is thus probably organized as a size exclusion matrix and this controls the rate of exchange of molecules with the extrasynaptic membrane.
Renner
Marianne L
ML
Physiologie Cellulaire de la Synapse, CNRS (UMR 5091), Université Bordeaux, Institut François Magendie, 146 rue Leo Saignat, 33077 Bordeaux Cedex, France.
Cognet
Laurent
L
Lounis
Brahim
B
Triller
Antoine
A
Choquet
Daniel
D
D000818:Animals; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D004058:Diffusion / Q000187:drug effects; D004622:Embryo, Mammalian; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology*; D018698:Glutamic Acid / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology; D009474:Neurons / Q000166:cytology*; D010714:Phosphatidylethanolamines / Q000494:pharmacology; D051381:Rats; D018091:Receptors, AMPA / Q000378:metabolism; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013570:Synaptic Membranes
C410262:1,2-dioleoyl-glycero-3-phosphatidyl ethanolamine; D018690:Excitatory Amino Acid Agonists; D010714:Phosphatidylethanolamines; D018091:Receptors, AMPA; D018698:Glutamic Acid; D002772:Cholera Toxin