Cloning of a novel glutamate receptor subunit, GluR5: Expression in the nervous system during development

We have isolated cDNAs encoding a glutamate receptor subunit, designated GluR5, displaying 40%–41% amino acid identity with the kainate/AMPA receptor subunits GluR1, GIuR2, GIuR3, and GIuR4. This level of sequence similarity is significantly below the approximately 70% intersubunit identity characteristic of kainate/AMPA receptors. The GIuR5 protein forms homomeric ion channels in Xenopus oocytes that are weakly responsive to L-glutamate. The GIuR5 gene is expressed in subsets of neurons throughout the developing and adult central and peripheral nervous systems. During embryogenesis, GluR5 transcripts are detected in areas of neuronal differentiation and synapse formation.