Henley J M, Oswald R E
Department of Pharmacology, New York State College of Veterinary Medicine, Cornell University, Ithaca 14850.
J Neurosci. 1988 Jun;8(6):2101-7. doi: 10.1523/JNEUROSCI.08-06-02101.1988.
The binding of several ligands that selectively interact with glutamate receptor subtypes was characterized in extensively washed synaptosomal membrane preparations from goldfish brain. The binding affinity (Kd), an estimate of the number of sites (Bmax), the rank-order potency of glutamatergic ligands at inhibiting binding, and the regional localization of binding sites were determined. In whole brain preparations, 3H-kainate had a Kd of 136 nM and a Bmax of 63 pmol/mg protein, 3H-AMPA had a Kd of 26 nM and a Bmax of 0.4 pmol/mg protein, and 3H-L-glutamate bound with an apparent affinity of 323 nM and a Bmax of 5 pmol/mg protein. Most of the binding sites for each of the glutamate analogs were present in the cortex and the fewest were in the cerebellum, except for 3H-kainate binding sites, which were most prevalent in the cerebellum and least abundant in the cortex. The proposed neuronal nicotinic acetylcholine receptor (nAChR) ligands 3H-(-)nicotine and 125I-alpha-Bgt were also investigated. 125I-alpha-Bgt had a Kd of 0.08 nM and a Bmax of 132 fmol/mg protein. 3H-(-)nicotine did not bind to the extensively washed membrane preparations, so a less stringently washed P2 tissue fraction was used. In this tissue preparation, 3H-(-)nicotine had a Kd of 9 nM and a Bmax of 84 fmol/mg protein. Eye removal resulted in a time-dependent decrease in the number of 3H-(-)nicotine and 125I-alpha-Bgt binding sites in the contralateral optic tectum, but no reduction in the number of binding sites for any of the glutamatergic ligands. The results suggest that both 3H-(-)nicotine and 125I-alpha-Bgt binding sites are similarly regulated in the optic tectum, which supports previously reported data indicating that the binding sites are located on closely related proteins or may, at least partially, be colocalized on the same protein (Henley and Oswald, 1987).(ABSTRACT TRUNCATED AT 250 WORDS)
在经过充分洗涤的金鱼脑突触体膜制剂中，对几种与谷氨酸受体亚型选择性相互作用的配体的结合特性进行了表征。测定了结合亲和力（Kd）、位点数量估计值（Bmax）、谷氨酸能配体抑制结合的效价排序以及结合位点的区域定位。在全脑制剂中，3H-海人酸的Kd为136 nM，Bmax为63 pmol/mg蛋白；3H-AMPA的Kd为26 nM，Bmax为0.4 pmol/mg蛋白；3H-L-谷氨酸的表观亲和力为323 nM，Bmax为5 pmol/mg蛋白。除了3H-海人酸结合位点在小脑最普遍而在皮层最少外，每种谷氨酸类似物的大多数结合位点都存在于皮层，而在小脑中最少。还研究了拟议的神经元烟碱型乙酰胆碱受体（nAChR）配体3H-（-）尼古丁和125I-α-银环蛇毒素。125I-α-银环蛇毒素的Kd为0.08 nM，Bmax为132 fmol/mg蛋白。3H-（-）尼古丁不与充分洗涤的膜制剂结合，因此使用了洗涤不太严格的P2组织部分。在这种组织制剂中，3H-（-）尼古丁的Kd为9 nM，Bmax为84 fmol/mg蛋白。摘除眼球导致对侧视顶盖中3H-（-）尼古丁和125I-α-银环蛇毒素结合位点的数量随时间减少，但任何谷氨酸能配体的结合位点数量均未减少。结果表明，视顶盖中3H-（-）尼古丁和125I-α-银环蛇毒素结合位点的调节方式相似，这支持了先前报道的数据，表明这些结合位点位于密切相关的蛋白质上，或者至少部分可能共定位在同一蛋白质上（亨利和奥斯瓦尔德，1987年）。（摘要截断于250字）
