Gotti C, Ogando A E, Hanke W, Schlue R, Moretti M, Clementi F
Consiglio Nazionale delle Ricerche Center of Cytopharmacology, University of Milan, Italy.
Proc Natl Acad Sci U S A. 1991 Apr 15;88(8):3258-62. doi: 10.1073/pnas.88.8.3258.
Neither the structure nor the function of alpha-bungarotoxin (alpha Bgtx) binding molecules in the nervous system have yet been completely defined, although it is known that some of these molecules are related to cation channels and some are not. Using an improved method of affinity chromatography, we have isolated a toxin binding molecule from chicken optic lobe that contains at least three subunits with apparent Mr values of 52,000, 57,000, and 67,000. The Mr 57,000 subunit binds alpha Bgtx and seems to be present in two copies per receptor. The receptor is recognized by antibodies raised against the alpha Bgtx receptors of human neuroblastoma cells, fetal calf muscle, and chicken optic lobe but not by antibodies raised against Torpedo acetylcholine receptor, the serum of myasthenic patients, or monoclonal antibody, 35. 125I-labeled alpha Bgtx binding to the isolated receptor is blocked, with the same potency, by nicotinic agonists and antagonists, such as nicotine, neuronal bungarotoxin and, d-tubocurarine. When reconstituted in a planar lipid bilayer, the purified alpha Bgtx receptor forms cationic channels with a conductance of 50 pS. These channels are activated in a dose-dependent manner by carbamylcholine and blocked by d-tubocurarine.
尽管已知神经系统中α-银环蛇毒素（αBgtx）结合分子的一些与阳离子通道有关，一些则无关，但这些分子的结构和功能尚未完全明确。我们使用改进的亲和层析方法，从鸡视叶中分离出一种毒素结合分子，它至少包含三个亚基，其表观分子量分别为52,000、57,000和67,000。分子量为57,000的亚基能结合αBgtx，且每个受体似乎有两个拷贝。该受体可被针对人神经母细胞瘤细胞、胎牛肌肉和鸡视叶的αBgtx受体产生的抗体识别，但不能被针对电鳐乙酰胆碱受体、重症肌无力患者血清或单克隆抗体35产生的抗体识别。125I标记的αBgtx与分离出的受体结合可被烟碱激动剂和拮抗剂，如尼古丁、神经元型银环蛇毒素和d -筒箭毒碱，以相同效力阻断。当在平面脂质双分子层中重组时，纯化的αBgtx受体形成电导为50 pS的阳离子通道。这些通道被氨甲酰胆碱以剂量依赖方式激活，并被d -筒箭毒碱阻断。
