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Ca2+/calmodulin-kinase II Enhances Channel Conductance of α -amino-3-hydroxy-5-methyl-4-isoxazolepropionate Type Glutamate Receptors

Victor Derkach, Andres Barria and Thomas R. Soderling
Proceedings of the National Academy of Sciences of the United States of America
Vol. 96, No. 6 (Mar. 16, 1999), pp. 3269-3274
Stable URL: http://www.jstor.org/stable/47525
Page Count: 6
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Since scans are not currently available to screen readers, please contact JSTOR User Support for access. We'll provide a PDF copy for your screen reader.
Ca2+/calmodulin-kinase II Enhances Channel Conductance of α -amino-3-hydroxy-5-methyl-4-isoxazolepropionate Type Glutamate Receptors
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Abstract

The ability of central glutamatergic synapses to change their strength in response to the intensity of synaptic input, which occurs, for example, in long-term potentiation (LTP), is thought to provide a cellular basis for memory formation and learning. LTP in the CA1 field of the hippocampus requires activation of Ca2+/calmodul II (CaM-KII), which phosphorylates Ser-831 in the GluR1 subunit of the α -amino-3-hydroxy-5-methyl-4-isoxazolepropionate glutamate receptor (AMPA-R), and this activation/phosphorylation is thought to be a postsynaptic mechanism in LTP. In this study, we have identified a molecular mechanism by which CaM-KII potentiates AMPA-Rs. Coexpression in HEK-293 cells of activated CaM-KII with GluR1 did not affect the glutamate affinity of the receptor, the kinetics of desensitization and recovery, channel rectification, open probability, or gating. Single-channel recordings identified multiple conductance states for GluR1, and coexpression with CaM-KII or a mutation of Ser-831 to Asp increased the contribution of the higher conductance states. These results indicate that CaM-KII can mediate plasticity at glutamatergic synapses by increasing single-channel conductance of existing functional AMPA-Rs or by recruiting new high-conductance-state AMPA-Rs.

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