A COMBINED COMPUTATIONAL AND EXPERIMENTAL STUDY ON THE LIGAND-GATING IN CNG AND

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 cAMP和cGMP是两种重要的细胞内第二信使，介导广泛的细胞过程。除了直接激活蛋白激酶，cAMP和cGMP还通过直接结合到环核苷酸门控（CNG）和超极化激活阳离子（HCN）通道的细胞内环核苷酸结合结构域（CNBD）来调节几种类型的离子通道的功能。这些离子通道在人体感觉、心血管和中枢神经系统中发挥重要作用。每个通道亚基包含六个跨膜结构域、C末端的CNBD和其间的接头区。最近发表的离子通道的相关结构揭示了这么多的机制洞察通道功能。然而，从静态图像中获得的信息总是有限的。计算方法和HCN 2通道CNBD晶体结构的最新进展为联合收割机结合实验和理论方法研究HCN/CNG通道中配体门控的本质提供了一个很好的机会。我们正在使用分子动力学和其他计算技术，以获得更多的见解配体结合和构象耦合的通道开放。CNBD的分子动力学模拟和突变型HCN 2通道的电生理学表征的初步数据提供了许多见解，并有助于澄清几个重要问题。我们相信，分配适当的计算时间将大大促进目前的模拟项目，并有助于获得更深入的了解CNG和HCN通道中的配体门控。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. cAMP and cGMP are two important intracellular second messengers mediating a wide range of cellular processes. Other than direct activating protein kinases, cAMP and cGMP also modulate the function of several types of ion channels through the direct binding to the intracellular cyclic-nucleotide binding domain (CNBD) of the cyclic-nucleotide gated (CNG) and hyperpolarization-activated cation (HCN) channels. These ion channels play important roles in the human sensory, cardiovascular and central nervous systems. Each channel subunit contains a six-transmembrane domain, a CNBD in the C-terminus and a linker region in between. Recently published ion channel related structures have revealed so much mechanistic insights into the channel function. However, the information from a static picture is always limited. Recent advances in computational methodologies and the crystal structure of the CNBD of HCN2 channel make a prefect opportunity to combine the experimental and theoretical approaches to tackle the nature of the ligand-gating in HCN/CNG channels. We are using molecular dynamics and other computational techniques to gain more insights into the ligand binding and the conformational coupling to the channel opening. Preliminary data from molecular dynamics simulation of the CNBD and the electrophysiological characterization of mutant HCN2 channels provided many insights and helped to clarify several important issues. We believe that the allocation of appropriate amount of computational time would facilitate the current simulation projects dramatically and help to obtain a deeper understanding of the ligand-gating in CNG and HCN channels.