Stephenson F A
J Recept Res. 1987;7(1-4):43-54. doi: 10.3109/10799898709054978.
The GABA receptor of mammalian brain is a ligand-gated channel protein with allosteric binding sites for the benzodiazepines and barbiturate drugs. The receptor is an acidic oligomeric membrane glycoprotein and it has been purified to homogeneity from bovine cerebral cortex, bovine cerebellum and rat cerebral cortex by benzodiazepine affinity chromatography. In each case, extraction and purification with the zwitterionic detergent CHAPS and exogenous phospholipid has demonstrated the coexistence of GABA, benzodiazepine and cage convulsant ligand binding sites on a single protein complex; in addition the allosteric interactions between these sites are preserved in the isolated protein. The receptor has a heterologous structure that is conserved at the subunit level between the aforementioned mammalian species and brain regions. SDS-PAGE has shown that the receptor consists of two subunits, alpha (Mr 53000) and beta (Mr 57000) present in equal stoichiometry. A model consistent with the determination of the molecular weight of the native protein, i.e., Mr 230,000, is that of a tetramer alpha 2 beta 2. [3H]Flunitrazepam and [3H]muscimol have been employed as photoaffinity labels to map the benzodiazepine and GABA binding polypeptides respectively. Polyclonal and monoclonal antibodies have been raised to the native bovine GABAA receptor and these have been employed for the further characterisation of the receptor protein.
哺乳动物脑内的γ-氨基丁酸（GABA）受体是一种配体门控通道蛋白，具有苯二氮䓬类和巴比妥类药物的变构结合位点。该受体是一种酸性寡聚膜糖蛋白，已通过苯二氮䓬亲和色谱法从牛脑皮层、牛小脑和大鼠脑皮层中纯化至均一状态。在每种情况下，用两性离子去污剂CHAPS和外源性磷脂进行提取和纯化，都证明了GABA、苯二氮䓬和惊厥配体结合位点在单一蛋白质复合物上共存；此外，这些位点之间的变构相互作用在分离的蛋白质中得以保留。该受体具有异源结构，在上述哺乳动物物种和脑区的亚基水平上是保守的。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）表明，该受体由两个亚基组成，α亚基（分子量53000）和β亚基（分子量57000），化学计量比相等。与天然蛋白质分子量测定结果（即分子量230000）一致的模型是四聚体α2β2。[3H]氟硝西泮和[3H]蝇蕈醇已被用作光亲和标记物，分别绘制苯二氮䓬和GABA结合多肽图谱。已经制备了针对天然牛GABAA受体的多克隆抗体和单克隆抗体，并将其用于受体蛋白的进一步表征。
