Hinoi E, Ogita K, Takeuchi Y, Ohashi H, Maruyama T, Yoneda Y
Department of Molecular Pharmacology, Kanazawa University Faculty of Pharmaceutical Sciences, 13-1 Takara-machi, Kanazawa, 920-0934, Ishikawa, Japan.
Brain Res. 2000 Oct 27;881(2):199-203. doi: 10.1016/s0006-8993(00)02809-2.
[3H]Quisqualic acid (QA) was synthesized and used to label metabotropic glutamate receptor (mGluR) in rat brain synaptic membranes in the presence of three different ionotropic glutamate receptor agonists at respective saturating concentrations. Of several mGluR agonists tested, group I agonists were more potent in displacing [3H]QA binding than group II and group III agonists in the presence of the three ionotropic agonists. [3H]QA binding was markedly inhibited by guanine nucleotide analogues in a concentration-dependent manner at a concentration range of 10 nM to 1 mM. Scatchard analysis revealed that [3H]QA binding consisted of a single component with a K(d) of 50.9+/-5.3 nM and a B(max) of 431. 6+/-18.3 fmol/mg protein. These results suggest that [3H]QA indeed labels group I mGluR functionally coupled to GTP binding protein in rat brain synaptic membranes when determined under the experimental conditions employed.
合成了[3H]喹啉酸（QA），并在三种不同的离子型谷氨酸受体激动剂分别处于饱和浓度的情况下，用其标记大鼠脑突触膜中的代谢型谷氨酸受体（mGluR）。在测试的几种mGluR激动剂中，在三种离子型激动剂存在的情况下，I组激动剂在取代[3H]QA结合方面比II组和III组激动剂更有效。在10 nM至1 mM的浓度范围内，鸟嘌呤核苷酸类似物以浓度依赖性方式显著抑制[3H]QA结合。Scatchard分析表明，[3H]QA结合由单一成分组成，解离常数（K(d)）为50.9±5.3 nM，最大结合容量（B(max)）为431.6±18.3 fmol/mg蛋白质。这些结果表明，在所采用的实验条件下测定时，[3H]QA确实标记了大鼠脑突触膜中与GTP结合蛋白功能偶联的I组mGluR。
