Nakajima T, Kurabayashi M, Ohyama Y, Kaneko Y, Furukawa T, Itoh T, Taniguchi Y, Tanaka T, Nakamura Y, Hiraoka M, Nagai R
Second Department of Internal Medicine, Gunma University School of Medicine, Showa-Machi, Maebashi, Gunma 371-8511, Japan.
FEBS Lett. 2000 Sep 15;481(2):197-203. doi: 10.1016/s0014-5793(00)01988-8.
We examined the mechanism(s) for HERG channel dysfunction in an S818L mutation in the HERG C-terminus using the heterologous expression system in Xenopus oocytes. Injection of S818L cRNA alone did not produce expressed currents. Coinjection of an equal amount of S818L cRNA with wild-type (WT) cRNA into oocytes did not exhibit apparent dominant-negative suppression. However, coinjection of excess amounts of S818L cRNAs with WT cRNA into oocytes decreased HERG current amplitudes and shifted the voltage dependence of activation to negative potentials, accelerated its activation and deactivation. The data suggest that S818L alone cannot form functional channels, whereas S818L subunits can, at least in part, coassemble with WT subunits to form heterotetrameric functional channels, and imply that the HERG C-terminus may contain a domain involving the activation-deactivation process of the channel. These findings may provide new insights into the structure-function relationships of the HERG C-terminus.
我们利用非洲爪蟾卵母细胞中的异源表达系统，研究了HERG C末端S818L突变导致HERG通道功能障碍的机制。单独注射S818L的cRNA未产生表达电流。将等量的S818L cRNA与野生型（WT）cRNA共同注射到卵母细胞中，未表现出明显的显性负性抑制作用。然而，将过量的S818L cRNA与WT cRNA共同注射到卵母细胞中，会降低HERG电流幅度，并将激活的电压依赖性向负电位方向移动，加速其激活和失活。数据表明，单独的S818L不能形成功能性通道，而S818L亚基至少可以部分地与WT亚基共同组装形成异源四聚体功能性通道，这意味着HERG C末端可能包含一个涉及通道激活-失活过程的结构域。这些发现可能为HERG C末端的结构-功能关系提供新的见解。
