Charybdotoxin binding in the IKs pore demonstrates two MinK subunits in each channel complex
Charybdotoxin binding in the IKs pore demonstrates two MinK subunits in each channel complex
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DOI：
10.1016/s0896-6273(03)00570-1
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发表时间：
2003-09-25
期刊：
影响因子：
16.2
通讯作者：
Goldstein, SAN
中科院分区：
文献类型：
--
作者：
Chen, HJ;Kim, LA;Goldstein, SAN
I-Ks电压门控K+通道包含4个成孔KCNQ1亚基和MinK附属亚基，其数量一直存在争议。在这里，将由单体亚基自然组装的i - k通道与具有强制定义化学计量的连接亚基的通道进行比较。两种策略利用肉毒杆菌毒素（CTX）敏感亚基变体应用。首先，CTX的开启速率、关闭速率和平衡亲和性对于单体通道和那些具有固定2:4 MinK:KCNQ1价的通道是相同的。其次，使用H-3-CTX和抗体分别直接定量通道和MinK亚基，每个I-Ks通道显示1.97 +/- 0.07 MinK。额外的MinK亚基不会进入单体亚基或固定的2:4价的通道。我们得出结论，两个MinK亚基是必要的，充分的，并且是i - k通道的规范。这种化学计量也适用于其他含有MinK或MinK相关肽（MiRPs）的K+通道。
I-Ks voltage-gated K+ channels contain four pore-forming KCNQ1 subunits and MinK accessory subunits in a number that has been controversial. Here, I-Ks channels assembled naturally by monomer subunits are compared to those with linked subunits that force defined stoichiometries. Two strategies that exploit charybdotoxin (CTX)-sensitive subunit variants are applied. First, CTX on rate, off rate, and equilibrium affinity are found to be the same for channels of monomers and those with a fixed 2:4 MinK:KCNQ1 valence. Second, H-3-CTX and an antibody are used to directly quantify channels and MinK subunits, respectively, showing 1.97 +/- 0.07 MinK per I-Ks channel. Additional MinK subunits do not enter channels of monomeric subunits or those with fixed 2:4 valence. We conclude that two MinK subunits are necessary, sufficient, and the norm in I-Ks channels. This stoichiometry is expected for other K+ channels that contain MinK or MinK-related peptides (MiRPs).