Raftery M A, Hunkapiller M W, Strader C D, Hood L E
Science. 1980 Jun 27;208(4451):1454-6. doi: 10.1126/science.7384786.
The acetylcholine receptor from the electric ray Torpedo californica is composed of five subunits; two are identical and the other three are structurally related to them. Microsequence analysis of the four polypeptides demonstrates amino acid homology among the subunits. Further sequence analysis of both membrane-bound and Triton-solubilized, chromatographically purified receptor gave the stoichiometry of the four subunits (40,000:50,000:60,000:65,000 daltons) as 2:1:1:1, indicating that this protein is a pentameric complex with a molecular weight of 255,000 daltons. Genealogical analysis suggests that divergence from a common ancestral gene occurred early in the evolution of the receptor. This shared ancestry argues that each of the four subunits plays a functional role in the receptor's physiological action.
加州电鳐的乙酰胆碱受体由五个亚基组成；其中两个亚基是相同的，另外三个亚基在结构上与它们相关。对这四种多肽的微序列分析表明，各亚基之间存在氨基酸同源性。对膜结合型和经Triton增溶、色谱纯化后的受体进行的进一步序列分析，得出四种亚基（分子量分别为40,000、50,000、60,000和65,000道尔顿）的化学计量比为2:1:1:1，这表明该蛋白质是一种分子量为255,000道尔顿的五聚体复合物。系统发育分析表明，受体进化早期就出现了与共同祖先基因的分化。这种共同的祖先关系表明，四个亚基中的每一个在受体的生理作用中都发挥着功能作用。
