GluR6/KA2 kainate receptors mediate slow-deactivating currents.
Kainate receptors (KARs) are ionotropic glutamate receptors contributing to EPSCs with a slow-decaying component that is likely essential for synaptic integration. The slow kinetics of KAR-EPSCs markedly contrasts with the fast kinetics reported for recombinant KARs expressed in heterologous systems, for reasons that remain unexplained. Here we have studied the properties of recombinant heteromeric GluR6/KA2 receptors, which compose synaptic KARs. We report that, in response to brief glutamate applications, currents mediated by recombinant GluR6/KA2 receptors, but not GluR6 receptors, decay with a time course similar to KAR-EPSCs. Model simulations suggest that, after brief agonist exposures, GluR6/KA2 currents undergo slow deactivation caused by the stabilization of partially bound open states. We propose, therefore, that the GluR6/KA2 gating features could contribute to the slow KAR-EPSC decay kinetics.
Laboratoire Physiologie Cellulaire de la Synapse, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5091, Bordeaux Neuroscience Institute, University of Bordeaux 2, 33077 Bordeaux, France. andrea.barberis@iit.it
Andrea
A
Barberis
Shankar
S
Sachidhanandam
Christophe
C
Mulle
D002460:Cell Line; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology; D019599:Mossy Fibers, Hippocampal / Q000502:physiology; D018092:Kainic Acid Receptors / Q000502:physiology*; D009435:Synaptic Transmission / Q000502:physiology*; D013997:Time Factors; D000097806:GluK2 Kainate Receptor
D018092:Kainic Acid Receptors; D000097806:GluK2 Kainate Receptor; C511773:GRIK5 protein, human