Shamotienko O G, Parcej D N, Dolly J O
Department of Biochemistry, Imperial College, London SW7 2AY, U.K.
Biochemistry. 1997 Jul 8;36(27):8195-201. doi: 10.1021/bi970237g.
Voltage-dependent Shaker-related (Kv1) K+ channels are composed of transmembrane alpha subunits and peripheral Kv beta proteins that exist as octomers with (alpha)4(beta)4 stoichiometry. Although several alpha (designated Kv1.X) and three Kv beta subunits are known to be expressed in brain, their oligomeric combinations in neurons have yet to be deciphered. Herein, the subunits comprising a number of neuronal K+ channels from bovine brain cortex were deduced by immunoprecipitation and Western blotting, using antibodies specific for Kv1.X and Kv beta subtypes. Only a subset of the theoretically possible oligomers was detected, showing that the synthesis and/or assembly of these multisubunit K+ proteins is controlled to yield a limited variety of K+ channels. Except for a small population of Kv1.4 containing K+ channels, all the recognizable species contained Kv1.2 and beta2 subunits. Furthermore, several subpopulations were identified including a fully defined complex of Kv1.2/1.3/1.4/1.6 and Kv beta2, plus oligomers containing three or two assigned alpha subunits. Kv1.2 was also shown to occur in the absence of these other subunits as a putative homo-oligomer. Thus, for the first time, the complete subunit combination of an authentic K+ channel has been elucidated; also, the strategy employed to establish this can now be applied to closely related members of other K+ channel families.
电压依赖性震颤相关（Kv1）钾通道由跨膜α亚基和外周Kvβ蛋白组成，它们以（α）4（β）4化学计量比的八聚体形式存在。尽管已知几种α亚基（命名为Kv1.X）和三种Kvβ亚基在脑中表达，但它们在神经元中的寡聚体组合尚未被破译。在此，使用针对Kv1.X和Kvβ亚型的特异性抗体，通过免疫沉淀和蛋白质印迹法推导了牛脑皮质中多种神经元钾通道的亚基组成。仅检测到理论上可能的寡聚体的一个子集，表明这些多亚基钾蛋白的合成和/或组装受到控制，以产生有限种类的钾通道。除了一小部分含有Kv1.4的钾通道外，所有可识别的种类都含有Kv1.2和β2亚基。此外，还鉴定了几个亚群，包括一个完全确定的Kv1.2/1.3/1.4/1.6和Kvβ2复合物，以及含有三个或两个指定α亚基的寡聚体。Kv1.2也被证明在没有这些其他亚基的情况下作为推定的同型寡聚体存在。因此，首次阐明了真实钾通道的完整亚基组合；此外，用于确定这一组合的策略现在可以应用于其他钾通道家族的密切相关成员。
