Transfer of rapid inactivation and sensitivity to the class III antiarrhythmic drug E-4031 from HERG to M-eag channels
Transfer of rapid inactivation and sensitivity to the class III antiarrhythmic drug E-4031 from HERG to M-eag channels
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DOI：
10.1111/j.1469-7793.1998.003bi.x
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发表时间：
1998-08-15
影响因子：
5.5
通讯作者：
Robertson, GA
中科院分区：
文献类型：
--
作者：
Herzberg, IM;Trudeau, MC;Robertson, GA
1. HERG的门控行为和药理学敏感性与结构相似的钾通道家族成员M-eag的相应性质明显不同。与HERG相比，m - eg没有明显失活，几乎没有整流，对III类抗心律失常药物E-4031.2不敏感。我们生成了HERG和M-eag序列的嵌合通道，并进行了点突变，以确定HERG中快速失活所需的区域。该区域包括P区和一半的S6推定跨膜结构域，包括先前未与herg失活和整改相关的位点。一小段HERG多肽转移到M-eaf；主要由P区和部分S6跨膜结构域组成，足以导致快速失活和E-4031。对m - ag的敏感性。这个区域与m - eg的相应区域仅相差15个残基。先前的假设认为，HERG通道的快速失活是通过c型失活机制发生的，这一假设得到了对HERG速率的平行影响的支持：多肽序列中两个等效位点的一系列突变导致HERG失活和Shaker c型失活。除了先前描述的Shaker中c型失活的同源位点外，HERG的失活还涉及上游P区的残基，以前与c型失活无关。尽管该位点与Kv2.1通道中p型失活的位点相同，但我们的数据与单一的c型失活机制最为一致。
1. The gating behaviour and pharmacological sensitivity of HERG are remarkably different from the corresponding properties of M-eag, a structurally similar member of the fag family of potassium channels. In contrast to HERG, M-eag exhibits no apparent inactivation and little rectification, and is insensitive to the class III antiarrhythmic drug E-4031.2. We generated chimeric channels of HERG and M-eag sequences and made point mutations to identify the region necessary for rapid inactivation in HERG. This region includes the P region and half of the S6 putative transmembrane domain, including sites not previously associated with inactivation and rectification in HERG.3. Transfer of a small segment of the HERG polypeptide to M-eaf;, consisting largely of the P region and part of the S6 transmembrane domain, is sufficient to confer rapid inactivation and E-4031. sensitivity to M-eag. This region differs from the corresponding region in M-eag by only fifteen residues.4. Previous hypotheses that rapid inactivation of HERG channels occurs by a C-type inactivation mechanism are supported by the parallel effects on rates of HERG: inactivation and Shaker C-type inactivation by a series of mutations at two equivalent sites in the polypeptide sequences.5. In addition to sites homologous to those previously described for C-type inactivation in Shaker, inactivation in HERG: involves a residue in the upstream P region not previously associated with C-type inactivation. Although this site is equivalent to one implicated in P-type inactivation in Kv2.1 channels, our data are most consistent with a single, C-type inactivation mechanism.