Cysteine modification alters voltage- and Ca(2+)-dependent gating of large conductance (BK) potassium channels.
Cysteine modification alters voltage- and Ca(2+)-dependent gating of large conductance (BK) potassium channels.
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DOI：
10.1085/jgp.200409149
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发表时间：
2005-02
期刊：
影响因子：
--
通讯作者：
Horrigan FT
中科院分区：
文献类型：
--
作者：
Zhang G;Horrigan FT
Ca 2+激活的K+（BK）通道α亚基在其大的COOH末端尾域中含有许多半胱氨酸残基。为了探索该结构域的功能，我们研究了半胱氨酸修饰剂对通道门控的影响。应用MTSET，MTSES，或NEM的mSlo 1或hSlo 1通道改变了电压和Ca 2+依赖的稳态激活。这些试剂似乎修饰相同的半胱氨酸，但对功能有不同的影响。MTSET增加IK并使GK-V关系向更负的电压移动，而MTSES和NEM使GK-V向相反方向移动。稳态激活在Ca 2+的存在或不存在下以及在电压传感器未被激活的负电位下被改变。还鉴定了[Ca 2 +]和电压的组合，其中Po不被半胱氨酸修饰改变。我们的结果的解释变构模型表明，半胱氨酸修饰改变Ca 2+的结合和相对稳定性的封闭和开放的构象，以及耦合的电压传感器激活和Ca 2+的结合和通道开放。为了鉴定修饰敏感的残基，我们检查了MTS试剂对缺乏一个或多个半胱氨酸的突变通道的影响。令人惊讶的是，MTSES对电压和Ca 2+依赖性门控的影响通过用丙氨酸取代单个半胱氨酸（C430）而被消除。C430位于BK通道特有的一系列八个残基内的RCK 1（K+电导调节因子）结构域中。这些残基的缺失使GK-V关系移动了>−80 mV。因此，我们已经确定了一个区域，似乎强烈影响RCK结构域的功能，但不存在已知结构的RCK结构域。C430 A不能消除MTSET对表观Ca ~（2+）亲和力的影响。然而，额外的突变，C615 S，在血红素结合位点减少MTSET的影响，与该区域在Ca 2+结合中的作用一致。
The Ca2+-activated K+ (BK) channel α-subunit contains many cysteine residues within its large COOH-terminal tail domain. To probe the function of this domain, we examined effects of cysteine-modifying reagents on channel gating. Application of MTSET, MTSES, or NEM to mSlo1 or hSlo1 channels changed the voltage and Ca2+ dependence of steady-state activation. These reagents appear to modify the same cysteines but have different effects on function. MTSET increases IK and shifts the GK–V relation to more negative voltages, whereas MTSES and NEM shift the GK–V in the opposite direction. Steady-state activation was altered in the presence or absence of Ca2+ and at negative potentials where voltage sensors are not activated. Combinations of [Ca2+] and voltage were also identified where Po is not changed by cysteine modification. Interpretation of our results in terms of an allosteric model indicate that cysteine modification alters Ca2+ binding and the relative stability of closed and open conformations as well as the coupling of voltage sensor activation and Ca2+ binding and to channel opening. To identify modification-sensitive residues, we examined effects of MTS reagents on mutant channels lacking one or more cysteines. Surprisingly, the effects of MTSES on both voltage- and Ca2+-dependent gating were abolished by replacing a single cysteine (C430) with alanine. C430 lies in the RCK1 (regulator of K+ conductance) domain within a series of eight residues that is unique to BK channels. Deletion of these residues shifted the GK–V relation by >−80 mV. Thus we have identified a region that appears to strongly influence RCK domain function, but is absent from RCK domains of known structure. C430A did not eliminate effects of MTSET on apparent Ca2+ affinity. However an additional mutation, C615S, in the Haem binding site reduced the effects of MTSET, consistent with a role for this region in Ca2+ binding.
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影响因子：
2.9
作者：
Cui, JM;Aldrich, RW
通讯作者：
Aldrich, RW
内部BA2+与平滑肌的克隆Ca（2+） - 依赖性K+（HSLO）通道的相互作用。
影响因子：
3.8
作者：
Diaz, F;Wallner, M;Stefani, E;Toro, L;Latorre, R
通讯作者：
Latorre, R
DOI：
10.1085/jgp.109.5.647
发表时间：
1997-05
期刊：
The Journal of general physiology
影响因子：
--
作者：
Cui J;Cox DH;Aldrich RW
通讯作者：
Aldrich RW
影响因子：
4.8
作者：
Brenner, R;Jegla, TJ;Aldrich, RW
通讯作者：
Aldrich, RW
影响因子：
3.4
作者：
Avdonin, V;Tang, XD;Hoshi, T
通讯作者：
Hoshi, T