RAT GLUR7 AND A CARBOXY-TERMINAL SPLICE VARIANT, GLUR7B, ARE FUNCTIONAL KAINATE RECEPTOR SUBUNITS WITH A LOW-SENSITIVITY TO GLUTAMATE

Glutamate receptors of the kainate-preferring subtype have recently be en shown to mediate synaptic transmission in the hippocampus. The low- affinity kainate receptor subunit GluR7 was found to be nonfunctional in previous studies. We report here that the GluR7 subunit and a novel carboxy-terminal splice variant, GluR7b, are functional glutamate rec eptors with unique pharmacological properties. In particular, glutamat e exhibits a 10-fold lower potency for (non-desensitized) GluR7-mediat ed currents as compared to other non-NMDA receptor channels. These dat a will facilitate understanding of the distinct role played by GluR7 r eceptors in synaptic transmission.