Molecular domains determining gap junction channel properties

决定间隙连接通道特性的分子域

• 批准号: 288241-2013
• 负责人: Bai, Donglin
• 金额: $ 2.19万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2013
• 资助国家: 加拿大
• 起止时间: 2013-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=525750
• 关键词: Molecular; domains; determining; gap; junction

Gap junction channels are specialized membrane pore structures between neighbouring cells, allowing ions and small molecules in one cell to pass on to the neighbour cells. The building blocks for gap junction channels are a group of transmembrane proteins called connexins (Cx). There are 20 different types of connexins are identified in rodents. Six identical connexins or different connexins form a cylinder-shaped half gap junction channel known as hemichannel. End-to-end docking of two hemichannels forms a complete gap junction channel. Communications through gap junction channels are essential for synchronized and coordinated cellular activities in tissues and organs. The gap junction channel pore size, the switch control for opening/closing, and the modulations by chemicals are different depending on the channel component connexin subtypes. This proposal aims to reveal which part of the connexin molecule is responsible for the distinct channel functional properties of the neuronal connexin, Cx36, and the eye lens connexin, Cx50. We plan to switch the key pore-lining domains from Cx36 into Cx50 or vise versa to generate Cx50 or Cx36 chimeras. These chimera proteins will be expressed into gap junction-deficient cells for functional test of gap junction channel properties. Further subdivision of positively identified domain will be used to track down the minimum amino acid residue(s) required to display unique functional properties. The proposed research will assist us in understanding the molecular mechanisms in the control of opening/closing of these important channels and the molecular determinants for the ability of the channel to conduct ions. A comprehensive knowledge of structure-function relationships for gap junction channels in neurons and in the lens is critical in the understanding of the physiological functions of these important intercellular channels.

间隙连接通道是相邻细胞之间的特殊膜孔结构，允许一个细胞中的离子和小分子传递到相邻细胞。缝隙连接通道的构建模块是一组称为连接蛋白（Cx）的跨膜蛋白。在啮齿类动物中发现了20种不同类型的连接蛋白。六个相同或不同的连接蛋白形成一个圆柱形的半间隙连接通道，称为半通道。两个半通道端到端对接形成完整的间隙连接通道。通过间隙连接通道的通信对于组织和器官中同步和协调的细胞活动是必不可少的。根据不同的通道成分连接蛋白亚型，缝隙连接通道的孔径大小、打开/关闭的开关控制以及化学物质的调节都是不同的。本研究旨在揭示连接蛋白分子的哪一部分负责神经元连接蛋白Cx36和眼晶状体连接蛋白Cx50的不同通道功能特性。我们计划将关键的孔衬结构域从Cx36切换到Cx50，反之亦然，以生成Cx50或Cx36嵌合体。这些嵌合体蛋白将在间隙连接缺陷细胞中表达，用于间隙连接通道特性的功能测试。进一步细分确定的结构域将用于追踪显示独特功能特性所需的最小氨基酸残基。所提出的研究将有助于我们了解控制这些重要通道的打开/关闭的分子机制以及通道传导离子能力的分子决定因素。全面了解神经元和晶状体间隙连接通道的结构-功能关系对于理解这些重要的细胞间通道的生理功能至关重要。