Large conductance voltage- and calcium-dependent K+ channel, a distinct member of voltage-dependent ion channels with seven N-terminal transmembrane segments (SO-S6), an extracellular N terminus, and an intracellular (S9-S10) C terminus
Large conductance voltage- and calcium-dependent K+ channel, a distinct member of voltage-dependent ion channels with seven N-terminal transmembrane segments (SO-S6), an extracellular N terminus, and an intracellular (S9-S10) C terminus
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DOI：
10.1073/pnas.94.25.14066
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发表时间：
1997-12-09
影响因子：
11.1
通讯作者：
Toro, L
中科院分区：
文献类型：
--
作者：
Meera, P;Wallner, M;Toro, L
大电导电压和Ca 2+依赖性K+（MaxiK）通道显示出与电压门控离子通道的序列相似性。它们具有同源的S1-S6区域，但在N和C末端是独特的。在C末端，MaxiK通道具有四个未知拓扑结构的额外疏水区域（S7-S10）。在N端，我们最近提出了一个新的模型，其中MaxiK通道具有额外的跨膜区（S 0），赋予β亚基调控。使用表位标记的MaxiK通道的瞬时表达、体外翻译、功能和“体内”重建测定，我们现在显示MaxiK通道在N末端具有七个跨膜区段（S 0-SG）和S1-S6区域，其以与电压门控离子通道中类似的方式折叠。我们的结果表明C末端的疏水片段S9-S10是细胞质的，并明确地证明SO形成了一个额外的跨膜片段，导致胞外N末端。
Large conductance voltage-and Ca2+-dependent K+ (MaxiK) channels show sequence similarities to voltage-gated ion channels. They have a homologous S1-S6 region, but are unique at the N and C termini. At the C terminus, MaxiK channels have four additional hydrophobic regions (S7-S10) of unknown topology. At the N terminus, we have recently proposed a new model where MaxiK channels hare an additional transmembrane region (S0) that confers beta subunit regulation. Using transient expression of epitope tagged MaxiK channels, in vitro translation, functional, and ''in vivo'' reconstitution assays, we now show that MaxiK channels have seven transmembrane segments (S0-SG) at the N terminus and a S1-S6 region that folds in a similar may as in voltage-gated ion channels, Further, our results indicate that hydrophobic segments S9-S10 in the C terminus are cytoplasmic and unequivocally demonstrate that SO forms an additional transmembrane segment leading to an exoplasmic N terminus.