IDENTIFICATION OF MOLECULAR-COMPONENTS OF A-TYPE CHANNELS ACTIVATING AT SUBTHRESHOLD POTENTIALS
IDENTIFICATION OF MOLECULAR-COMPONENTS OF A-TYPE CHANNELS ACTIVATING AT SUBTHRESHOLD POTENTIALS
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DOI：
10.1152/jn.1994.72.4.1516
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发表时间：
1994-10-01
影响因子：
2.5
通讯作者：
RUDY, B
中科院分区：
文献类型：
--
作者：
SERODIO, P;KENTROS, C;RUDY, B
1. 注射了大鼠脑mRNA的爪蟾卵母细胞表达一种类似于a电流的瞬时KC电流，该电流在体细胞神经元记录的Na+动作电位产生（I-SA）的阈值附近短暂激活。我们使用反义寡核苷酸杂交阻滞来研究克隆的K+通道蛋白中哪些可能是负责脑mRNA表达的I-SA通道的组分。与所有已知哺乳动物shal相关mrna共有的序列互补的寡核苷酸[KV4.1, KV4.2和KV4.3（本文使用了Chandy及其同事的shk +通道基因的命名法）]阻断了I-SA的表达。仅与KV4.2 mRNA互补的寡核苷酸，是大鼠脑RNA制剂中最丰富的shal相关转录物，也非常有效地阻止脑I-SA的表达。这些实验表明，在注入脑mRNA的卵母细胞中，shal相关蛋白是携带I-SA通道的重要组成部分。然而，这种I-SA与体外转录的KV4.1或KV4.2 cRNA在相同卵母细胞中表达的电流存在一些显著差异。如果将KV4.1或KV4.2 cRNA与经过反义寡核苷酸处理的脑聚(A) RNA（可抑制I-SA的表达）或2-4Kb大鼠脑聚(A) RNA片段（在相同的记录条件下不表达可检测的K+电流）共注射，则大多数这些差异将被消除。这些数据支持了一种假设，即脑mRNA表达的I-SA通道含有Shal蛋白，这些蛋白可以被自身不表达K+电流的rna编码的蛋白修饰。
1. Xenopus oocytes injected with rat brain mRNA express a transient KC current similar to the A current that activates transiently near the threshold for Na+ action potential generation (I-SA) seen in somatic recordings from neurons. We used hybrid arrest with antisense oligonucleotides to investigate which of the cloned K+ channel proteins might be components of the channels responsible for the I-SA expressed from brain mRNA. An oligonucleotide complementary to a sequence common to all known mammalian Shal-related mRNAs [KV4.1, KV4.2, and KV4.3 (the nomenclature of Sh K+ channel genes of Chandy and colleagues was used in this paper)] blocked the expression of the I-SA. An oligonucleotide complementary only to the KV4.2 mRNA, the most abundant Shal-related transcript in rat brain RNA preparations, was also quite efficient in arresting the expression of the I-SA from brain. These experiments indicate that Shal-related proteins are important components of the channels carrying the I-SA expressed in oocytes injected with brain mRNA. However, there are several significant differences between this I-SA and the currents expressed in the same oocytes by in vitro transcribed KV4.1 or KV4.2 cRNA. Most of these differences are eliminated if KV4.1 or KV4.2 cRNA is coinjected with brain poly-(A) RNA treated with antisense oligonucleotides which arrest the expression of the I-SA, or with a 2-4Kb rat brain poly-(A) RNA fraction which does not express detectable K+ currents under the same recording conditions. These data support the hypothesis that I-SA channels such as those expressed from brain mRNA contain Shal proteins that can be modified by proteins encoded in RNAs that by themselves do not express K+ currents.