Structural basis for modulation and agonist specificity of HCN pacemaker channels
Structural basis for modulation and agonist specificity of HCN pacemaker channels
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DOI：
10.1038/nature01922
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发表时间：
2003-09-11
期刊：
影响因子：
64.8
通讯作者：
Gouaux, E
中科院分区：
文献类型：
--
作者：
Zagotta, WN;Olivier, NB;Gouaux, E
超极化激活、环核苷酸调节（HCN）通道家族对一系列电信号至关重要，包括心脏和神经元起搏器活动、静息膜电特性和树突整合(1)。这些非选择性阳离子通道是心脏和神经细胞的I-f、I-h和I-q电流的基础，它们被膜超极化激活，并被环核苷酸如cAMP和cGMP的结合调节(2)。camp介导的通道活性增强是β -肾上腺素能激动剂引起心率增加的主要原因(3)。在这里，我们通过研究含有环核苷酸结合域（CNBD）的HCN2的羧基末端片段和连接CNBD和孔的c连接子区域来研究这种调节的机制。结合cAMP或cGMP的c端片段的x射线晶体结构，以及平衡沉降分析，确定了一个四聚域和环核苷酸特异性的机制，并提出了一个配体依赖的通道调制模型。基于与HCN通道的氨基酸序列相似性，环核苷酸门控、eag和kat1相关的通道家族可能在结构和机制上与HCN通道相关。
The family of hyperpolarization-activated, cyclic nucleotide-modulated (HCN) channels are crucial for a range of electrical signalling, including cardiac and neuronal pacemaker activity, setting resting membrane electrical properties and dendritic integration(1). These nonselective cation channels, underlying the I-f, I-h and I-q currents of heart and nerve cells, are activated by membrane hyperpolarization and modulated by the binding of cyclic nucleotides such as cAMP and cGMP(2). The cAMP-mediated enhancement of channel activity is largely responsible for the increase in heart rate caused by beta-adrenergic agonists(3). Here we have investigated the mechanism underlying this modulation by studying a carboxy-terminal fragment of HCN2 containing the cyclic nucleotide-binding domain (CNBD) and the C-linker region that connects the CNBD to the pore. X-ray crystallographic structures of this C-terminal fragment bound to cAMP or cGMP, together with equilibrium sedimentation analysis, identify a tetramerization domain and the mechanism for cyclic nucleotide specificity, and suggest a model for ligand-dependent channel modulation. On the basis of amino acid sequence similarity to HCN channels, the cyclic nucleotide-gated, and eag- and KAT1-related families of channels are probably related to HCN channels in structure and mechanism.