Functional characterization of a prokaryotic Kir channel.
Functional characterization of a prokaryotic Kir channel.
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DOI：
10.1074/jbc.c400417200
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发表时间：
2004-11-05
期刊：
影响因子：
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通讯作者：
Nichols CG
中科院分区：
文献类型：
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作者：
Enkvetchakul D;Bhattacharyya J;Jeliazkova I;Groesbeck DK;Cukras CA;Nichols CG
Kir基因家族编码内向整流K+（Kir）通道，其是真核细胞中广泛存在的和关键的兴奋性调节剂。最近在原核生物中发现了一个相关基因家族（KirBac）。虽然其中一个成员KirBac 1.1的晶体结构已经得到解决，但还没有任何KirBac基因产物的功能表征。在这里，我们提出了在脂质体中重构的KirBac1.1的功能表征。利用86 Rb+摄取测定，我们证明KirBac1.1产生的K+-选择性渗透路径，抑制由extraliposomal Ba 2+和Ca 2+离子。与KcsA（酸激活的细菌钾通道）相反，KirBac1.1被脂质体外酸抑制（pKa ~ 6）。KirBac1.1活性的这种表征现在为该模型Kir通道中结构和功能的进一步相关性铺平了道路。
The Kir gene family encodes inward rectifying K+ (Kir) channels that are widespread and critical regulators of excitability in eukaryotic cells. A related gene family (KirBac) has recently been identified in prokaryotes. While a crystal structure of one member, KirBac1.1, has been solved, there has been no functional characterization of any KirBac gene products. Here we present functional characterization of KirBac1.1 reconstituted in liposomes. Utilizing a 86Rb+ uptake assay, we demonstrate that KirBac1.1 generates a K+-selective permeation path that is inhibited by extraliposomal Ba2+ and Ca2+ ions. In contrast to KcsA (an acid-activated bacterial potassium channel), KirBac1.1 is inhibited by extraliposomal acid (pKa ~ 6). This characterization of KirBac1.1 activity now paves the way for further correlation of structure and function in this model Kir channel.