Silent TWIK-1 Potassium Channels Conduct Monovalent Cation Currents
Silent TWIK-1 Potassium Channels Conduct Monovalent Cation Currents
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DOI：
10.1016/j.bpj.2012.03.011
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发表时间：
2012-04-18
影响因子：
3.4
通讯作者：
Chen, Haijun
中科院分区：
文献类型：
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作者：
Ma, Liqun;Xie, Yu-Ping;Chen, Haijun
在生理离子条件下，TWIK-1双孔域K+通道在异源表达系统中通常产生不可测量的或非常低水平的K+电流。两种有争议的机制被提出来解释这种行为：TWIK-1 K+通道在细胞表面表达，但在赖氨酸残基上被sumoylation沉默（TWIK-1 K274）；TWIK-1的构成性和快速内化导致TWIK-1通道沉默。在这里，我们报道了在中国仓鼠卵巢细胞中异种表达的TWIK-1 K+通道，在生理K+梯度下沉默，当细胞外离子条件改变时，能够传导大的单价阳离子电流。这些结果支持了TWIK-1 K+通道在细胞表面表达但沉默的假设，并表明TWIK-1的门控行为而不是细胞表面缺乏表达导致异种表达系统中无法检测到TWIK-1 K+电流。
TWIK-1 two-pore domain K+ channels generally produce nonmeasurable or very low levels of K+ currents in heterologous expression systems under physiologically ionic conditions. Two controversial mechanisms have been proposed to account for this behavior: TWIK-1 K+ channels are expressed in the cell surface but silenced by sumoylation at a lysine residue (TWIK-1 K274); constitutive and rapid internalization of TWIK-1 causes TWIK-1 channel silencing. Here we report that TWIK-1 K+ channels heterologously expressed in Chinese hamster ovary cells, which are silent in physiological K+ gradients, are able to conduct large monovalent cation currents when extracellular ionic conditions change. These results support the hypothesis that TWIK-1 K+ channels are expressed in the cell surface but silent, and suggest that the TWIK-1 gating behavior rather than the lack of cell surface expression of TWIK-1 results in nondetectable TWIK-1 K+ currents in heterologous expression systems.