Hamilton S L
Prog Clin Biol Res. 1982;79:73-85.
The nicotinic acetylcholine receptor of the electric ray is currently one of the most extensively studied integral membrane proteins. A very speculative model for the structure of acetylcholine receptor in the membrane is shown in Fig. 1. This model does not take into account the extremely high density of receptor in the subsynaptic region of the membrane. The receptor is an oligomeric glycoprotein composed of five subunits, all of which are exposed externally, span the lipid bilayer, and are exposed cytoplasmically. Although the subunits have considerable sequence homology, they arise from the translation of different messenger RNAs. The naturally occurring form of the Torpedo receptor is a dimer, but monomer is also functionally active. Each receptor monomer has two binding sites for agonists and competitive antagonists but probably only one site for specific binding of local anesthetics. This latter site appears to be in the open ion channel near the center of the membrane.
电鳐的烟碱型乙酰胆碱受体是目前研究最为广泛的整合膜蛋白之一。图1展示了一种关于膜中乙酰胆碱受体结构的极具推测性的模型。该模型未考虑到膜突触下区域受体的极高密度。受体是一种由五个亚基组成的寡聚糖蛋白，所有亚基都向外暴露，跨越脂质双层，并在细胞质中暴露。尽管亚基具有相当程度的序列同源性，但它们来自不同信使RNA的翻译。电鳐受体的天然形式是二聚体，但单体也具有功能活性。每个受体单体有两个激动剂和竞争性拮抗剂的结合位点，但可能只有一个局部麻醉药特异性结合位点。后一个位点似乎位于膜中心附近的开放离子通道中。
