The properties of the Kir6.1-6.2 tandem channel co-expressed with SUR2A
The properties of the Kir6.1-6.2 tandem channel co-expressed with SUR2A
复制标题
DOI：
10.1007/s004240000315
复制
发表时间：
2000-09-01
影响因子：
4.5
通讯作者：
Sasayama, S
中科院分区：
文献类型：
--
作者：
Kono, Y;Horie, M;Sasayama, S
功能性ATP敏感性K（K-ATP）通道具有八聚体亚基结构，其具有四个孔形成亚基（Kir6.x）和四个磺酰脲受体（SURx）。在本研究中，异源表达系统，其孔亚基组成的Kir6.1和Kir6.2的异源性K-ATP通道的性质进行了研究。在以1：1：2的比例共转染Kir6.1、Kir6.2和SUR 2A的COS 7细胞中，K-ATP通道在Kir6.1/SUR 2A（33.6+/-4.2 pS）和Kir6.2/SUR 2A（67.1+/-1.6 pS）之间显示出不同的单位电导。Kir6.1-6.2串联蛋白通过将Kir6.1的C-末端与Kir6.2的N-末端用10个谷氨酰胺接头序列融合而构建，也形成具有中等电导（58.9+/-1.5pS）的通道。Kir6.2和Kir6.1-6.2对ATP（4-）的敏感性相似：半数最大抑制（IC 50）分别为14.1+/-12.8 μ M和17.6+/-9.6 μ M。在Mg 2+存在的情况下，Kir6.1-6.2对MgATP的敏感性显著低于Kir6.2（IC 50 =95.5+/-49.6 muM vs 18.9+/-5.0 muM）。这些结果表明Kir6.1和Kir6.2具有形成异聚K-ATP通道的潜力，其对MgATP具有低敏感性。
Functional ATP-sensitive K (K-ATP) channels have an octameric subunit structure with four pore-forming subunits (Kir6.x) and four sulfonylurea receptors (SURx). In the present study, the properties of the het eromeric K-ATP channel whose pore subunits are composed of Kir6.1 and Kir6.2 were examined using a heterologous expression system. In COS7 cells co-transfected with Kir6.1, Kir6.2 and SUR2A at a ratio of 1:1:2, K-ATP channels showed various unitary conductances between those of Kir6.1/SUR2A (33.6+/-4.2 pS) and Kir6.2/SUR2A (67.1+/-1.6 pS). Kir6.1-6.2 tandem protein, constructed by fusing the C-terminus of Kir6.1 to the N-terminus of Kir6.2 with a ten glutamine linker sequence, also formed a channel with an intermediate conductance (58.9+/-1.5 pS). Kir6.2 and Kir6.1-6.2 showed similar sensitivity to ATP(4-): half-maximal inhibition (IC50) was obtained at 14.1+/-12.8 muM and 17.6+/-9.6 muM, respectively. In the presence of Mg2+, Kir6.1-6.2 was significantly less sensitive than Kir6.2 to MgATP (IC50=95.5+/-49.6 muM versus 18.9+/-5.0 muM). These results suggest that Kir6.1 and Kir6.2 are endowed with the potential to form a heteromeric K-ATP channel, which has a low sensitivity to MgATP.