Noda M, Takahashi H, Tanabe T, Toyosato M, Kikyotani S, Furutani Y, Hirose T, Takashima H, Inayama S, Miyata T, Numa S
Nature. 1983 Apr 7;302(5908):528-32. doi: 10.1038/302528a0.
The nicotinic acetylcholine receptor (AChR) from the electroplax of the ray Torpedo californica is composed of five subunits present in a molar stoichiometry of alpha 2 beta gamma delta (refs 1-3) and contains both the binding site for the neurotransmitter and the cation gating unit (reviewed in refs 4-6). We have recently elucidated the complete primary structures of the alpha-, beta- and delta-subunit precursors of the T. californica AChR by cloning and sequencing cDNAs for these polypeptides. Here, we report the whole primary structure of the gamma-subunit precursor of the AChR deduced from the nucleotide sequence of the cloned cDNA. Comparison of the amino acid sequences of the four subunits reveals marked homology among them. The close resemblance among the hydrophilicity profiles and predicted secondary structures of all the subunits suggests that these polypeptides are oriented in a pseudosymmetric fashion across the membrane. Each subunit contains four putative transmembrane segments that may be involved in the ionic channel. The transmembrane topology of the subunit molecules has also been inferred.
加州电鳐电器官中的烟碱型乙酰胆碱受体（AChR）由五个亚基组成，其摩尔化学计量比为α2βγδ（参考文献1 - 3），它既包含神经递质的结合位点，也包含阳离子门控单元（参考文献4 - 6中有综述）。我们最近通过克隆和测序这些多肽的cDNA，阐明了加州电鳐AChR的α、β和δ亚基前体的完整一级结构。在此，我们报告从克隆的cDNA核苷酸序列推导出来的AChRγ亚基前体的完整一级结构。四个亚基的氨基酸序列比较显示它们之间有显著的同源性。所有亚基的亲水性图谱和预测的二级结构非常相似，这表明这些多肽以假对称方式跨膜排列。每个亚基包含四个可能参与离子通道的假定跨膜片段。还推断出了亚基分子的跨膜拓扑结构。
