Abstract
Glutamatergic neurotransmission is controlled by presynaptic metabotropic glutamate receptors (mGluRs). A subdomain in the intracellular carboxyl-terminal tail of group III mGluRs binds calmodulin and heterotrimeric guanosine triphosphate-binding protein (G protein) betagamma subunits in a mutually exclusive manner. Mutations interfering with calmodulin binding and calmodulin antagonists inhibit G protein-mediated modulation of ionic currents by mGluR 7. Calmodulin antagonists also prevent inhibition of excitatory neurotransmission via presynaptic mGluRs. These results reveal a novel mechanism of presynaptic modulation in which Ca(2+)-calmodulin is required to release G protein betagamma subunits from the C-tail of group III mGluRs in order to mediate glutamatergic autoinhibition.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Calcium / metabolism
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Calmodulin / antagonists & inhibitors
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Calmodulin / metabolism*
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Cells, Cultured
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Dimerization
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G Protein-Coupled Inwardly-Rectifying Potassium Channels
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GTP-Binding Proteins / metabolism*
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Glutamic Acid / metabolism*
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Hippocampus / cytology
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Hippocampus / metabolism
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Humans
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Mice
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Molecular Sequence Data
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Neurons / metabolism
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Potassium Channels / metabolism
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Potassium Channels, Inwardly Rectifying*
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Presynaptic Terminals / metabolism
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Propionates / pharmacology
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Rats
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Rats, Sprague-Dawley
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Receptors, Metabotropic Glutamate / antagonists & inhibitors
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Receptors, Metabotropic Glutamate / metabolism*
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Recombinant Fusion Proteins / metabolism
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Sesterterpenes
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Signal Transduction
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Swine
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Synaptic Transmission*
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Terpenes / pharmacology
Substances
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2-amino-4-phosphono-propinate
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Calmodulin
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G Protein-Coupled Inwardly-Rectifying Potassium Channels
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Potassium Channels
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Potassium Channels, Inwardly Rectifying
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Propionates
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Receptors, Metabotropic Glutamate
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Recombinant Fusion Proteins
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Sesterterpenes
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Terpenes
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metabotropic glutamate receptor 7
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Glutamic Acid
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ophiobolin A
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GTP-Binding Proteins
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Calcium