Characterisation of Na+-Independent L-[3H]Glutamate Binding Sites in Human Temporal Cortex |
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Authors: | R. F. Cowburn J. A. Hardy P. J. Roberts |
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Affiliation: | Department of Biochemistry and Molecular Genetics, St. Mary's Hospital Medical School, Paddington, London, England. |
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Abstract: | The binding of L-[3H]glutamate to membranes from human temporal cortex was studied in the absence of Na+, Ca2+, and Cl- ions. Pharmacological characterisation revealed that approximately 35% of specific binding at 50 nM L-[3H]glutamate was sensitive to a combination of kainate and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid. The remaining approximately 65% of specific binding was to a single population of sites with a KD of 844 nM and a Bmax of 0.92 pmol/mg protein. The pharmacological characteristics were consistent with an interaction at the N-methyl-D-aspartate subclass of excitatory amino acid receptor. The inclusion of Cl- ions revealed additional glutamate binding; this was sensitive to quisqualate and DL-2-amino-4-phosphonobutyrate, but not to kainate, DL-2-amino-7-phosphonoheptanoate, or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid. |
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Keywords: | Glutamate receptors Human brain Postmortem N-Methyl-D-aspartate |
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