Noda M, Ikeda T, Kayano T, Suzuki H, Takeshima H, Kurasaki M, Takahashi H, Numa S
Nature. 1986;320(6058):188-92. doi: 10.1038/320188a0.
The sodium channel is a voltage-gated ionic channel essential for the generation of action potentials. It has been reported that the sodium channels purified from the electric organ of Electrophorus electricus (electric eel) and from chick cardiac muscle consist of a single polypeptide of relative molecular mass (Mr) approximately 260,000 (260K), whereas those purified from rat brain and skeletal muscle contain, in addition to the large polypeptide, two or three smaller polypeptides of Mr 37-45K. Recently, we have elucidated the primary structure of the Electrophorus sodium channel by cloning and sequencing the DNA complementary to its messenger RNA. Despite the apparent homogeneity of the purified sodium channel preparations, several types of tetrodotoxin (or saxitoxin) binding sites or sodium currents have been observed in many excitable membranes. The occurrence of distinguishable populations of sodium channels may be attributable to different states of the same channel protein or to distinct channel proteins. We have now isolated complementary DNA clones derived from two distinct rat brain mRNAs encoding sodium channel large polypeptides and present here the complete amino-acid sequences of the two polypeptides (designated sodium channels I and II), as deduced from the cDNA sequences. A partial DNA sequence complementary to a third homologous mRNA from rat brain has also been cloned.
钠通道是一种电压门控离子通道，对动作电位的产生至关重要。据报道，从电鳗的电器官和鸡心肌中纯化的钠通道由一条相对分子质量（Mr）约为260,000（260K）的单一多肽组成，而从大鼠脑和骨骼肌中纯化的钠通道，除了这条大的多肽外，还含有两条或三条Mr为37 - 45K的较小多肽。最近，我们通过克隆和测序与其信使RNA互补的DNA，阐明了电鳗钠通道的一级结构。尽管纯化的钠通道制剂表面上具有同质性，但在许多可兴奋膜中已观察到几种类型的河豚毒素（或石房蛤毒素）结合位点或钠电流。钠通道不同群体的出现可能归因于同一通道蛋白的不同状态或不同的通道蛋白。我们现在已经从两种不同的大鼠脑mRNA中分离出编码钠通道大多肽的互补DNA克隆，并在此呈现从cDNA序列推导的这两种多肽（命名为钠通道I和II）的完整氨基酸序列。与大鼠脑第三种同源mRNA互补的部分DNA序列也已被克隆。
