PROPERTIES OF VOLTAGE-GATED K+ CURRENTS EXPRESSED IN XENOPUS OOCYTES BY MKV1.1, MKV1.2 AND THEIR HETEROMULTIMERS AS REVEALED BY MUTAGENESIS OF THE DENDROTOXIN-BINDING SITE IN MKV1.1
PROPERTIES OF VOLTAGE-GATED K+ CURRENTS EXPRESSED IN XENOPUS OOCYTES BY MKV1.1, MKV1.2 AND THEIR HETEROMULTIMERS AS REVEALED BY MUTAGENESIS OF THE DENDROTOXIN-BINDING SITE IN MKV1.1
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DOI：
10.1007/bf00724522
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发表时间：
1994-10-01
影响因子：
4.5
通讯作者：
TEMPEL, BL
中科院分区：
文献类型：
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作者：
HOPKINS, WF;ALLEN, ML;TEMPEL, BL
两个相似的小鼠Shaker-Like K+通道基因mKv1.1和mKv1.2已被证明在体内形成异源多聚体。每个通道的预测氨基酸序列在小鼠、大鼠和人类中几乎相同，这表明每个通道在进化上都是高度保守的。在这里，我们报告的生物物理和药理学特性的每个通道时，单独表达或共同表达在非洲爪蟾卵母细胞。两者的激活电压敏感性相似，但对于mKv1.1和mKv1.2，K+电导达到半最大值（V-1/2）时的电压分别为-37 mV和-27 mV。两者都表现出电压依赖性，但不完全，失活后的预脉冲与mKv1.2显示thp更大程度的失活。对于mKv1.1，失活的开始和恢复可以用单个缓慢的时间常数（2-4 s）来描述，而对于mKv1.2，失活的开始和恢复显示出第二个更快的时间常数（< 400 ms）。使用突变mKv1.1，是100倍的敏感性比mKv1.1的树突状毒素-I，我们证明，这种突变mKv1.1和野生型mKv1.2亚基可以形成异源多聚体通道。除了一些未知意义的例外，野生型mKv1.1和mKv1.2亚基形成的异源多聚体通道的生物物理特性介于mKv1.1和mKv1.2同源多聚体之间，但在数量上更类似于更丰富的亚基。
Two similar mouse Shaker-Like K+ channel genes, mKv1.1 and mKv1.2, have been shown to form heteromultimers in vivo. The predicted amino acid sequence of each channel is nearly identical in mice, rats and humans, suggesting that each has been highly conserved evolutionarily. Here we report the biophysical and pharmacological properties of each channel when expressed alone or when coexpressed in Xenopus oocytes. The voltage sensitivities of activation were similar for both, but the voltages at which the K+ conductances were half-maximal (V-1/2) were -37 mV and -27 mV for mKv1.1 and mKv1.2 respectively. Both displayed voltage-dependent, but incomplete, inactivation following a prepulse with mKv1.2 showing thp greater degree of inactivation. For mKv1.1, the onset and recovery from inactivation could be described by single, slow time constants (2-4 s), whereas for mKv1.2 the onset and recovery from inactivation displayed a second, faster time constant (< 400 ms). Using a mutant mKv1.1 that is 100-fold less sensitive to dendrotoxin-I than mKv1.1, we demonstrate that this mutant mKv1.1 and wild-type mKv1.2 subunits can form heteromultimeric channels. With some exceptions, of unknown significance, the biophysical properties of the heteromultimeric channels formed by wild-type mKv1.1 and mKv1.2 subunits were intermediate between those of mKv1.1 and mKv1.2 homomultimers, but quantitatively more similar to the more abundant subunit.