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）：突触传播负责神经元之间的信息传递及其调节是学习，记忆和生理调节的许多方面的基础。 N型和P/Q-Type CA电流分别通过CAV2.1和CAV2.2通道，负责在大多数常规快速突触下启动神经递质释放的CA输入。通过突触前CA通道进入的CA形成了高CA浓度的局部结构域，该结构域激活近乎附近的胞吐作用。因此，突触囊泡必须在突触前CA通道附近停靠才能有效释放。神经递质释放取决于通过突触前CA通道的CA电流的第三或第四功率，因此CA进入的小变化对突触传播具有很大的影响。由于CA依赖性促进和突触传播灭活而引起的突触可塑性是信息编码和传播的重要决定因素。通过G蛋白偶联受体起作用的许多神经递质可以抑制突触前CA通道的活性，从而抑制突触传播。通过强烈的去极化或通过蛋白激酶C磷酸化来缓解它们的抑制作用。我们在本项目时期的结果给出了重要的新见解，以调节G蛋白对突触前CA通道的调节。我们已经分析了SNARE蛋白结合及其在突触蛋白相互作用位点的调节的结构功能关系，并且我们已经表明，该部位对于通过外源表达的CA通道重新建立了突触传播所必需。此外，我们发现了通过钙调蛋白和神经特异性Ca结合蛋白对CA通道调节的新机制，这些机制可能在短期突触可塑性中具有重要作用。在下一个项目时期，我们计划以这些进步为基础，以进一步定义CA通道功能的分子机制和突触传播中调节的调节。我们将通过神经特异性钙调蛋白（CAM）-ike Ca结合蛋白来确定CAV2.1通道调节的位点和机制。我们将进一步定义SNARE蛋白与CAV2.1通道的突触蛋白相互作用的相互作用位点，以及通过蛋白激酶C（PKC）和CA/CAM依赖性蛋白激酶II（CAMKIII）通过磷酸化来调节SNARE蛋白结合和CAV2.1通道功能。基于此分子信息，我们将分析神经特异性Ca结合蛋白，SNARE蛋白和蛋白质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，我们将通过CA结合蛋白，SNARE蛋白和蛋白质磷酸化来探测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播的机制和调节提供重要的新见解，并将进一步定义CAV2.1通道的功能及其在突触可塑性中的调节。