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Solubilization of Spermidine‐Sensitive (+)‐[ 3 H]5‐Methyl‐10,11 ‐Dihydro‐5 H ‐Dibenzo[ a,d ]cyclohepten‐5,10‐Imine ([ 3 H]MK‐801) Binding Activity from Rat Brain
Author(s) -
Ogita Kiyokazu,
Yoneda Yukio
Publication year - 1990
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1990.tb04933.x
Subject(s) - nmda receptor , chemistry , spermidine , sephadex , dizocilpine , glycine , spermine , ionophore , stereochemistry , receptor , biochemistry , membrane , amino acid , enzyme
The receptor‐ionophore complex of the N ‐methyl‐d‐aspartate (NMDA)‐sensitive receptor was solubilized by deoxycholic acid from rat brain using (+)‐[ 3 H]5‐methyl‐10,11‐dihydro‐5 H ‐dibenzo[ a,b ]cyclohepten‐5,10‐imine ([ 3 H]MK‐801) binding as a marker for the receptor. Gel filtration of the solubilized preparations on a Sephadex G‐25 column revealed significant [ 3 H]MK‐801 binding sensitive to potentiation by glutamate and glutamate/glycine, which was prevented by competitive antagonists for the NMDA and strychnine‐insensitive glycine (Gly B ) sites. In contrast to NMDA and glycine, spermidine markedly potentiated the amount of [ 3 H]MK‐801 binding in solubilized preparations by increasing the apparent affinity of the ligand. In the presence of all three stimulants, the solubilized preparations exhibited pharmacological profiles similar to those in the membrane preparations. These results clearly indicate that the whole macromolecular NMDA receptor‐ionophore complex is solubilized under the experimental conditions used.