Structure-Function Studies Of IP3R Channels

项目概要/摘要（家长奖） Ca 2+从内部储存的释放是由属于一个亚单位的肌醇1，4，5-三磷酸受体（IP 3R）介导的。 几乎在每个细胞中定位于内质网膜的细胞内Ca 2+通道家族 类型. Ca 2+通过IP 3R通道的快速流动是许多和显著不同的细胞的核心。 从收缩到分泌，从增殖到细胞死亡。IP 3R功能障碍 与许多神经退行性疾病，如阿尔茨海默氏病和亨廷顿病，心脏病， 心律失常、自身免疫性疾病、共济失调、中风和癌症。尽管IP 3R的重要性已经确立， 生理学和病理学，这些通道的功能背后的分子机制，无论是在天然和 疾病状态，仍然知之甚少。这主要是由于缺乏IP 3R的原子级细节 结构我们研究的长期目标是了解离子渗透和门控的机制 在IP 3R通道家族中，以及细胞内结合伴侣如何调节通道功能。重点 神经元1型IP 3R（IP 3R 1）是IP 3门控Ca 2+释放通道的主要类型， 小脑浦肯野细胞这一建议建立在我们最近在结构研究方面取得的广泛进展的基础上。 这个离子通道我们的目标是揭示IP 3R 1的高分辨率架构，并描绘构象 通道的变化，是其门控运动和细胞内分子阵列调节的基础 从离子和小的化合物到蛋白质。我们的研究工作将包括冷冻EM 结构测定、生物化学、生物物理学、诱变和电生理学研究， 渠道结构-功能建立在成熟的调查人员的互补专业知识基础上， 初步数据支持，拟议的研究将揭示IP 3R 1的结构和机制基础 功能，并将阐明如何在调节通道的门控机制的缺陷可能会导致异常 细胞Ca 2+水平是许多疾病的基础。我们的研究是创新性的，因为在原子能方面所知甚少。 关于IP 3R的功能。完成这些研究后，我们将建立一个详细的结构 理解IP 3R如何选择性地感知和解码多个配体结合信号， 门控运动，使Ca 2+通过通道。这些知识对于发展 控制通道功能的新方法。总的来说，拟议的研究非常重要，因为它们将提供 对Ca 2+跨生物膜转移的有价值的机制见解， Ca 2+信号转导失调的后果，这将最终有助于寻找针对糖尿病的新疗法。 IP 3R通道系列。

Project Summary/Abstract (parent award) Ca2+ release from internal stores is mediated by inositol 1,4,5-trisphosphate receptors (IP3R) that belong to a family of intracellular Ca2+ channels localized to the endoplasmic reticulum membranes in almost every cell type. The rapid flux of Ca2+ through IP3R channels is central to numerous and markedly different cellular actions, ranging from contraction to secretion, from proliferation to cell death. Dysfunction of IP3Rs is implicated in numerous neurodegenerative diseases, such as Alzheimer’s and Huntington’s disease, cardiac arrhythmias, autoimmune disease, ataxia, stroke and cancer. Despite established significance of IP3Rs in physiology and pathology, the molecular mechanisms underlying function of these channels, both in native and disease states, remain poorly understood. This is mainly due to the lack of atomic-level details of IP3R structure. The long-term goals of our research are to understand the mechanisms of ion permeation and gating in the family of IP3R channels, and how intracellular binding partners regulate the channel function. The focus of this proposal is neuronal type 1 IP3R (IP3R1), the predominant type of IP3-gated Ca2+ release channel in cerebellar Purkinje cells. This proposal builds on extensive advances we made recently in structural studies of this ion channel. We aim to uncover high-resolution architecture of IP3R1 and to delineate conformational changes in the channel that underlie its gating motion and regulation by an array of intracellular molecules ranging from ions and small chemical compounds to proteins. Our research efforts will include cryo-EM structure determination, biochemistry, biophysical, mutagenesis and electrophysiological studies to address channel structure-function Built upon the complementary expertise of established investigators with compelling preliminary data support, the proposed studies will unveil the structural and mechanistic basis for IP3R1 function and will elucidate how defects in mechanisms regulating the channel’s gating can lead to abnormal cell Ca2+ levels underlying numerous diseases. Our research is innovative since little is known at the atomic level about the IP3R function. With these studies accomplished, we will establish a detailed structural framework for understanding how the IP3R selectively senses and decodes multiple ligand-binding signals into gating motions that enable the passage of Ca2+ through the channel. This knowledge is crucial for developing new ways to control channel function. Overall, the proposed studies are highly significant, as they will provide valuable mechanistic insights into Ca2+ transfer across biological membranes illuminating the pathological consequences of deregulated Ca2+ signaling, that will ultimately aid in search for novel therapies targeting the IP3R channel family.