Trimmer J S, Cooperman S S, Tomiko S A, Zhou J Y, Crean S M, Boyle M B, Kallen R G, Sheng Z H, Barchi R L, Sigworth F J
Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, Connecticut 06510.
Neuron. 1989 Jul;3(1):33-49. doi: 10.1016/0896-6273(89)90113-x.
We describe the isolation and characterization of a cDNA encoding the alpha subunit of a new voltage-sensitive sodium channel, microI, from rat skeletal muscle. The 1840 amino acid microI peptide is homologous to alpha subunits from rat brain, but, like the protein from eel electroplax, lacks an extended (approximately 200) amino acid segment between homologous domains I and II. Northern blot analysis indicates that the 8.5 kb microI transcript is preferentially expressed in skeletal muscle. Sodium channels expressed in Xenopus oocytes from synthetic RNA encoding microI are blocked by tetrodotoxin and mu-conotoxin at concentrations near 5 nM. The expressed sodium channels have gating kinetics similar to the native channels in rat muscle fibers, except that inactivation occurs more slowly.
我们描述了从大鼠骨骼肌中分离并鉴定一种编码新型电压敏感性钠通道α亚基（microI）的cDNA的过程。该含1840个氨基酸的microI肽与大鼠脑内的α亚基同源，但与电鳗电板中的蛋白质一样，在同源结构域I和II之间缺少一段约200个氨基酸的延伸片段。Northern印迹分析表明，8.5 kb的microI转录本在骨骼肌中优先表达。从编码microI的合成RNA在非洲爪蟾卵母细胞中表达的钠通道，在浓度接近5 nM时被河豚毒素和μ-芋螺毒素阻断。所表达的钠通道的门控动力学与大鼠肌肉纤维中的天然通道相似，只是失活发生得更慢。
