Formation of functional heterodimers between the TASK-1 and TASK-3 two-pore domain potassium channel subunits
Formation of functional heterodimers between the TASK-1 and TASK-3 two-pore domain potassium channel subunits
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DOI：
10.1074/jbc.m107138200
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发表时间：
2002-02-15
影响因子：
4.8
通讯作者：
Enyedi, P
中科院分区：
文献类型：
--
作者：
Czirják, G;Enyedi, P
双孔结构域家族中的钾通道广泛表达并调节神经元和其他可兴奋细胞的兴奋性。这些通道已被证明以二聚体的形式发挥作用，但各种通道亚基之间的异聚化尚未见报道。在这里，我们证明钾通道 TASK 亚家族的两个成员 TASK-1 和 TASK-3 在非洲爪蟾卵母细胞中表达时可以形成功能性异二聚体。为了识别两种 TASK 通道类型，我们利用了 TASK-1 相对于 TASK-3 对生理 pH 变化更高的敏感性以及 TASK-3 对阳离子染料钌红的区分敏感性。当单独表达通道时，可以清楚地观察到这些特征。然而，当TASK-1和TASK-3一起表达时，产生的电流表现出中等pH敏感性和钌红不敏感性（TASK-1的特征），表明TASK-1/TASK-3异二聚体的形成。 TASK-3 和 TASK-1 连接在一起的串联构建体的表达产生的电流具有与共表达两个通道时观察到的特征非常相似的电流。串联构建体还对 AT(1A) 血管紧张素 II 受体刺激作出反应，其抑制作用弱于同二聚体 TASK-1 的抑制作用，但大于 TASK-3 所显示的抑制作用。哺乳动物细胞中表位标记通道的表达表明它们主要存在于质膜中，与其在该位置的功能一致。双孔结构域钾通道的异聚化可以提供更大的功能多样性和在其天然组织中调节它们的额外手段。
The potassium channels in the two-pore domain family are widely expressed and regulate the excitability of neurons and other excitable cells. These channels have been shown to function as dimers, but heteromerization between the various channel subunits has not yet been reported. Here we demonstrate that two members of the TASK subfamily of potassium channels, TASK-1 and TASK-3, can form functional heterodimers when expressed in Xenopus laevis oocytes. To recognize the two TASK channel types, we took advantage of the higher sensitivity of TASK-1 over TASK-3 to physiological pH changes and the discriminating sensitivity of TASK-3 to the cationic dye ruthenium red. These features were clearly observed when the channels were expressed individually. However, when TASK-1 and TASK-3 were expressed together, the resulting current showed intermediate pH sensitivity and ruthenium red insensitivity (characteristic of TASK-1), indicating the formation of TASK-1/TASK-3 heterodimers. Expression of a tandem construct in which TASK-3 and TASK-1 were linked together yielded currents with features very similar to those observed when coexpressing the two channels. The tandem construct also responded to AT(1A) angiotensin II receptor stimulation with an inhibition that was weaker than the inhibition of homodimeric TASK-1 and greater than that shown by TASK-3. Expression of epitope-tagged channels in mammalian cells showed their primary presence in the plasma membrane consistent with their function in this location. Heteromerization of two-pore domain potassium channels may provide a greater functional diversity and additional means by which they can be regulated in their native tissues.