Toyoda Futoshi, Ueyama Hisao, Ding Wei-Guang, Matsuura Hiroshi
Department of Physiology, Shiga University of Medical Science, Seta-Tsukinowa, Otsu, Shiga 520-2192, Japan.
Biochem Biophys Res Commun. 2006 Jun 9;344(3):814-20. doi: 10.1016/j.bbrc.2006.03.213. Epub 2006 Apr 19.
The KCNE proteins (KCNE1 through KCNE5) function as beta-subunits of several voltage-gated K(+) channels. Assembly of KCNQ1 K(+) channel alpha-subunits and KCNE1 underlies cardiac I(Ks), while KCNQ1 interacts with all other members of KCNE forming complexes with different properties. Here we investigated synergic actions of KCNE1 and KCNE2 on functional properties of KCNQ1 heterologously expressed in COS7 cells. Patch-clamp recordings from cells expressing KCNQ1 and KCNE1 exhibited the slowly activating current, while co-expression of KCNQ1 with KCNE2 produced a practically time-independent current. When KCNQ1 was co-expressed with both of KCNE1 and KCNE2, the membrane current exhibited a voltage- and time-dependent current whose characteristics differed substantially from those of the KCNQ1/KCNE1 current. The KCNQ1/KCNE1/KCNE2 current had a more depolarized activation voltage, a faster deactivation kinetics, and a less sensitivity to activation by mefenamic acid. These results suggest that KCNE2 can functionally couple to KCNQ1 even in the presence of KCNE1.
KCNE蛋白（KCNE1至KCNE5）作为几种电压门控钾通道的β亚基发挥作用。KCNQ1钾通道α亚基与KCNE1的组装是心脏I(Ks)的基础，而KCNQ1与KCNE的所有其他成员相互作用，形成具有不同特性的复合物。在此，我们研究了KCNE1和KCNE2对在COS7细胞中异源表达的KCNQ1功能特性的协同作用。对表达KCNQ1和KCNE1的细胞进行膜片钳记录，显示出缓慢激活的电流，而KCNQ1与KCNE2共表达则产生了几乎与时间无关的电流。当KCNQ1与KCNE1和KCNE2两者共表达时，膜电流呈现出电压和时间依赖性电流，其特性与KCNQ1/KCNE1电流有很大不同。KCNQ1/KCNE1/KCNE2电流具有更去极化的激活电压、更快的失活动力学以及对甲芬那酸激活的敏感性较低。这些结果表明，即使在存在KCNE1的情况下，KCNE2也能在功能上与KCNQ1偶联。
