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Characterization of 5,7‐Dichlorokynurenate‐Insensitive d ‐[ 3 H]Serine Binding to Synaptosomal Fraction Isolated from Rat Brain Tissues
Author(s) -
Matoba Masaki,
Tomita Urara,
Nishikawa Toru
Publication year - 1997
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 - 10.1046/j.1471-4159.1997.69010399.x
Subject(s) - serine , glycine , nmda receptor , glutamate receptor , binding site , biochemistry , biology , amino acid , chemistry , receptor , enzyme
To explore target sites for endogenous d ‐serine that are different from the glycine site of the N ‐methyl‐ d ‐aspartate (NMDA) type glutamate receptor, we have studied the binding of d ‐[ 3 H]serine to the synaptosomal P2 fraction prepared from the rat brain and peripheral tissues in the presence of an excess concentration (100 µ M ) of the glycine site antagonist 5,7‐dichlorokynurenate (DCK). Nonspecific binding was defined in the presence of 1 m M unlabeled d ‐serine. Association, dissociation, and saturation experiments indicated that d ‐[ 3 H]serine bound rapidly and reversibly to a single population of recognition sites in the cerebellar P2 fraction in the presence of DCK, with a K D of 614 n M and a B max of 2.07 pmol/mg of protein. d ‐Serine, l ‐serine, and glycine produced a total inhibition of the specific DCK‐insensitive d ‐[ 3 H]serine binding to the cerebellum with similar K i values. Strychnine and 7‐chlorokynurenate failed to inhibit the binding at 10 µ M . The profiles of displacement of the DCK‐insensitive d ‐[ 3 H]serine binding by various amino acids and glutamate and glycine receptor‐related compounds differ from those of any other defined recognition sites. DCK‐insensitive d ‐[ 3 H]serine binding was at high levels in the cerebral cortex and cerebellum but very low in the kidney and liver. The present findings indicate that the DCK‐insensitive d ‐[ 3 H]serine binding site could be a novel candidate for a target for endogenous d ‐serine in mammalian brains.