Ellisman M H, Levinson S R
Proc Natl Acad Sci U S A. 1982 Nov;79(21):6707-11. doi: 10.1073/pnas.79.21.6707.
The tetrodotoxin binding protein, a major component of the Na+ channel, has been purified from the electric organ of the South American eel Electrophorus electricus. Antibodies to this protein were raised in rabbits and their specificity was demonstrated by a highly sensitive radioimmunoassay and by immunoprecipitation procedures. These antibodies were used to examine the distribution of the binding protein in the eel electroplax membranes and along myelinated nerve axons. The distribution of the antigen was determined by using the peroxidase-antiperoxidase technique at both the light and electron microscopic levels. In the electrocytes of the electric organ, only the innervated face showed staining in experimental material. The stained regions of electroplax plasmalemma included the caveolae of the innervated surface while caveolae of the non-innervated surface did not stain. Thus, the innervated surface including caveolae exclusively contains the Na+ channels. Along myelinated axons, staining was limited to the nodal zone of the node of Ranvier. The paranodal and internodal zones did not stain for the binding protein. Limited diffusion of primary IgG and subsequent reactants into the paranodal and internodal sites was eliminated as a possible source of focal staining at nodes because mechanically demyelinated preparations also exhibited focal nodal staining. Thus, this tetrodotoxin binding protein component of the Na+ channel is located solely within the nodal zone of the node of Ranvier.
河豚毒素结合蛋白是钠离子通道的主要成分，已从南美电鳗电鳐的电器官中纯化出来。针对该蛋白的抗体在兔子体内产生，其特异性通过高灵敏度放射免疫测定法和免疫沉淀程序得以证明。这些抗体被用于检测结合蛋白在电鳗电板膜和有髓神经轴突中的分布。通过在光学和电子显微镜水平上使用过氧化物酶-抗过氧化物酶技术来确定抗原的分布。在电器官的电细胞中，在实验材料中只有受神经支配的面呈现染色。电板质膜的染色区域包括受神经支配表面的小窝，而未受神经支配表面的小窝则不染色。因此，包括小窝在内的受神经支配表面专门含有钠离子通道。沿着有髓轴突，染色仅限于郎飞结的结区。结旁区和结间区未显示结合蛋白染色。由于机械性脱髓鞘制剂也表现出结处的局灶性染色，因此排除了一级IgG和后续反应物向结旁和结间部位的有限扩散作为结处局灶性染色的可能来源。因此，钠离子通道的这种河豚毒素结合蛋白成分仅位于郎飞结的结区内。
