Homomeric GluR1 excitatory amino acid receptors expressed in Xenopus oocytes.
The GluR1 cDNA clone encodes a functional excitatory amino acid receptor (Hollmann et al., Nature 342: 643-648 (1989]. We have studied the pharmacological properties of this homomeric (single subunit) receptor expressed in Xenopus oocytes and compared these properties with those of receptors encoded by rat forebrain mRNA. (RS)-alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionate, quisqualate, and glutamate were partial agonists at both GluR1 and forebrain non-N-methyl-D-aspartate (-NMDA) receptors. The potency of the agonists kainate, domoate, and glutamate was higher, and that of the antagonists 6-cyano-7-nitro-quinoxalinedione and 6,7-dichloro-3-hydroxy-2-quinoxaline carboxylic acid lower, for GluR1 receptors as compared with forebrain non-NMDA receptors. The GluR1 receptor differed strikingly from forebrain-derived non-NMDA receptors, however, in that it exhibited slow, calcium-dependent desensitization. Thus, most properties of the GluR1 receptor are similar but not identical to those of non-NMDA receptors expressed from forebrain mRNA. These results indicate that the ligand recognition sites on GluR1 homomeric receptors are subtly different from those of non-NMDA receptors expressed from a mixture of forebrain mRNA.
Dawson
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TL
Department of Pharmacology, University of North Carolina, Chapel Hill 27599.
Nicholas
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Dingledine
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D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D000818:Animals; D018118:Chloride Channels; D005727:Ganglia, Spinal / Q000737:chemistry; D006624:Hippocampus / Q000737:chemistry; D007051:Ibotenic Acid / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D007608:Kainic Acid / Q000494:pharmacology; D008565:Membrane Proteins / Q000187:drug effects; D009865:Oocytes / Q000737:chemistry; D011810:Quinoxalines / Q000494:pharmacology; D016318:Quisqualic Acid / Q000494:pharmacology; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter / Q000032:analysis* / Q000187:drug effects / Q000235:genetics; D014981:Xenopus; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid
D018118:Chloride Channels; D008565:Membrane Proteins; D011810:Quinoxalines; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter; D007051:Ibotenic Acid; D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D016318:Quisqualic Acid; D007608:Kainic Acid