Structure-function studies of IP3R channels

项目摘要/摘要 三磷酸肌醇受体(IP3R)是细胞内定位于内质网的钙通道 几乎在每种细胞类型中都有网状膜。内质网钙离子通过IP3R通道的快速流动 到胞浆是许多明显不同的细胞活动的中心，从收缩到 分泌物，从增殖到细胞死亡。尽管IP3Rs在生理学和生物学上具有既定的意义 病理学，这些通道在自然状态和疾病状态下的潜在功能的分子机制， 人们对此仍然知之甚少。我们研究的长期目标是了解离子的机制。 IP3R通道家族中的渗透和门控，以及细胞内结合伙伴如何调节 通道功能。这项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。 神经元型IP3R(IP3R1)--小脑浦肯野主要的IP3门控钙释放通道 细胞。我们的目标是揭示整个四聚体IP3R1的高分辨率结构并描绘 通道的构象变化是其门控运动和细胞内一系列调控的基础 分子的范围从离子和小的化合物到蛋白质。我们的研究工作将包括低温- EM结构测定、生化、生物物理、诱变和电生理研究 地址通道结构-功能。建立在成熟调查人员的互补专业知识基础上 令人信服的初步数据支持，拟议的研究将揭示 IP3R的功能，并将阐明调节通道门控的机制中的缺陷如何导致 细胞内钙离子水平异常是许多疾病的基础。我们的研究是创新的，因为我们对 有关IP3R功能的原子级别。随着这些研究的完成，我们将建立一个详细的结构 理解IP3R如何选择性地感知和解码多个配体结合信号的框架 门控运动，使钙离子通过通道。这方面的知识对于发展 控制渠道功能的新方法。总体而言，拟议的研究具有重要意义，因为它们将提供 钙离子跨生物膜转运的有价值的机制洞察 去调控的钙信号转导的后果，这最终将有助于寻找针对 IP3R通道系列。

Project Summary/Abstract Inositol 1,4,5-trisphosphate receptors (IP3R) are intracellular Ca2+ channels localized to the endoplasmic reticulum (ER) membranes in almost every cell type. The rapid flux of Ca2+ through IP3R channels from the ER to the cytosol is central to numerous and markedly different cellular actions, ranging from contraction to secretion, from proliferation to cell death. 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. 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. This proposal builds on extensive advances we made recently in structural studies of neuronal type 1 IP3R (IP3R1), the predominant type of IP3-gated Ca2+ release channel in cerebellar Purkinje cells. We aim to uncover high-resolution architecture of the entire tetrameric 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 IP3R 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.