Molecular Properties of Voltage Sensitive Ca++ Channels

电压敏感 Ca 通道的分子特性

• 批准号: 6826349
• 负责人: WILLIAM A CATTERALL
• 金额: $ 35.06万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 1985
• 资助国家: 美国
• 起止时间: 1985-09-09 至 2008-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6826349
• 关键词: calcium channel; calmodulin; calmodulin dependent protein kinase; crosslink; electrophysiology; gene deletion mutation; hippocampus; immunoprecipitation; laboratory rat; nerve /myelin protein; neural plasticity; neural transmission; neuroregulation; phosphorylation; protein binding; protein kinase C; protein protein interaction; protein structure function; site directed mutagenesis; sympathetic ganglion; synaptosomes; synaptotagmin; tissue /cell culture; voltage /patch clamp; voltage gated channel

DESCRIPTION (provided by applicant): Synaptic transmission is responsible for information transfer between neurons and its regulation underlies learning, memory, and many aspects of physiological regulation. N-type and P/Q-type Ca currents through Cav2.1 and Cav2.2 channels, respectively, are responsible for the Ca entry that initiates neurotransmitter release at most conventional fast synapses. Ca entering through presynaptic Ca channels forms a local domain of high Ca concentration that activates exocytosis in the near vicinity. Therefore, synaptic vesicles must dock near presynaptic Ca channels to be efficiently released. Neurotransmitter release is dependent on the third or fourth power of the Ca current through presynaptic Ca channels, so small changes in Ca entry have large effects on synaptic transmission. Synaptic plasticity due to Ca-dependent facilitation and inactivation of synaptic transmission is an important determinant of information coding and transmission. Many neurotransmitters that act through G protein-coupled receptors can inhibit the activity of presynaptic Ca channels and thereby inhibit synaptic transmission. Their inhibition is relieved by strong depolarization or by phosphorylation by protein kinase C. Our results in the present project period have given important new insights into regulation of presynaptic Ca channels by G proteins. We have analyzed the structure-function relationships of SNARE protein binding and its regulation at the synaptic protein interaction site, and we have shown that this site is necessary for reconstitution of synaptic transmission by exogenously expressed Ca channels. In addition, we have discovered a novel mechanism of Ca channel regulation by calmodulin and neuro-specific Ca binding proteins, which are likely to have important roles in short-term synaptic plasticity. In the next project period, we plan to build on these advances to further define the molecular mechanism of Ca channel function and regulation in synaptic transmission. We will determine the sites and mechanisms of action and the diversity of regulation of Cav2.1 channels by neuro-specific calmodulin (CaM)-Iike Ca binding proteins. We will further define the site of interaction of SNARE proteins with the synaptic protein interaction site of Cav2.1 channels and the regulation of SNARE protein binding and Cav2.1 channel function by phosphorylation by protein kinase C (PKC) and Ca/CaM-dependent protein kinase II (CaMKII). Based on this molecular information, we will analyze the functional significance of neuro-specific Ca binding proteins, SNARE proteins, and protein phosphorylation in regulation of synaptic transmission neurons in cell culture. Finally, we will probe the convergent regulation of Cav2.1 channel function and synaptic transmission by Ca-binding proteins, SNARE proteins, and protein phosphorylation. These studies will give important new insight into the mechanism and regulation of synaptic transmission and will further define the function of Cav2.1 channels and their regulation in synaptic plasticity.

描述（由申请人提供）：突触传递负责神经元之间的信息传递，其调节是学习、记忆和生理调节的许多方面的基础。分别通过 Cav2.1 和 Cav2.2 通道的 N 型和 P/Q 型 Ca 电流负责在大多数传统快速突触处启动神经递质释放的 Ca 进入。 Ca 通过突触前 Ca 通道进入，形成高 Ca 浓度的局部区域，激活附近的胞吐作用。因此，突触小泡必须停靠在突触前 Ca2+ 通道附近才能有效释放。神经递质的释放取决于通过突触前 Ca2+ 通道的 Ca2+ 电流的三次方或四次方，因此 Ca2+ 进入的微小变化会对突触传递产生很大影响。由于 Ca 依赖性促进和突触传递失活而产生的突触可塑性是信息编码和传递的重要决定因素。许多通过G蛋白偶联受体发挥作用的神经递质可以抑制突触前Ca通道的活性，从而抑制突触传递。它们的抑制作用可以通过蛋白激酶 C 的强去极化或磷酸化来缓解。我们在当前项目期间的结果为 G 蛋白调节突触前 Ca 离子通道提供了重要的新见解。我们分析了 SNARE 蛋白结合的结构-功能关系及其在突触蛋白相互作用位点的调节，并表明该位点对于通过外源表达的 Ca 通道重建突触传递是必需的。此外，我们还发现了钙调蛋白和神经特异性 Ca 结合蛋白调节 Ca 通道的新机制，这可能在短期突触可塑性中发挥重要作用。在下一个项目期间，我们计划在这些进展的基础上进一步明确 Ca 通道功能和突触传递调节的分子机制。我们将确定神经特异性钙调蛋白 (CaM) 样 Ca 结合蛋白的作用位点和机制以及 Cav2.1 通道调节的多样性。我们将进一步定义 SNARE 蛋白与 Cav2.1 通道突触蛋白相互作用位点的相互作用位点，以及通过蛋白激酶 C (PKC) 磷酸化和 Ca/CaM 依赖来调节 SNARE 蛋白结合和 Cav2.1 通道功能蛋白激酶 II (CaMKII)。基于这些分子信息，我们将分析神经特异性 Ca 结合蛋白、SNARE 蛋白和蛋白磷酸化在细胞培养中突触传递神经元调节中的功能意义。最后，我们将探讨 Ca 结合蛋白、SNARE 蛋白和蛋白磷酸化对 Cav2.1 通道功能和突触传递的收敛调节。这些研究将为突触传递的机制和调节提供重要的新见解，并将进一步明确 Cav2.1 通道的功能及其在突触可塑性中的调节。