Ca regulation of Ca channels

Ca 通道的 Ca 调节

• 批准号: 9100519
• 负责人: Manu Ben Johny
• 金额: $ 33.13万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2018-01-01
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9100519
• 关键词: Address; Alanine; Arrhythmia; Binding; Biological; Biological Assay; Brain; Bypass; C-terminal; Calmodulin; Complement; Computer Simulation; Data; Dependence; Distant; Electrophysiology (science); Equation; Feedback; Fluorescence Resonance Energy Transfer; Goals; Harvest; Hybrids; Joints; Lead; Light; Link; Lobe; Measures; Microscope; Migraine; Molecular; N-terminal; Neurobiology; Neurodegenerative Disorders; Paramecium; Physiologic pulse; Physiological; Physiology; Potassium Channel; Process; Production; Property; Publications; RNA Editing; Regulation; Resolution; Scanning; Scheme; Signal Transduction; Site; Source; System; Technology; Therapeutic; Translations; Variant; Work; innovation; insight; prototype; response; sensor; theories; voltage

DESCRIPTION (provided by applicant): Calmodulin (CaM) regulation of CaV1-2 channels-termed calmodulation has proven rich, both biologically and as a general modulatory prototype with discriminating Ca2+ decoding capabilities. In earlier cycles, Ca2+-free CaM (apoCaM) was found to be pre-associated to an IQ domain on the intracellular carboxy terminus of channels. Ca2+-binding to this resident CaM induces as-yet-unclear conformational changes that somehow facilitate (CDF) or inactivate (CDI) channel opening, casting calmodulation as a positive or negative feedback control system for Ca2+. Intriguingly, Ca2+-binding to the C- and N-terminal lobes of CaM can each induce distinct forms of channel regulation, echoing earlier findings of CaM 'functional bipartition' in Paramecium. More remarkably, the C-lobe responds to the ~100-mM Ca2+ pulses driven by the associated channel (local Ca2+ selectivity), whereas the N-lobe is somehow capable of sensing far weaker signals from distant Ca2+ sources (global selectivity). In the current cycle, we deduced in coarse outline the functional mechanisms of calmodulation by the C-terminal lobe of CaM (slow CaM scheme), and by the N-terminal lobe (SQS scheme). These mechanisms explain the notable spatial Ca2+ decoding properties of these two calmodulatory subsystems. Prominently absent, however, is a quantitative sense of the Ca2+ dependence of these low-resolution mechanistic sketches, owing to the complexity of Ca2+ channel influx that normally drives calmodulation. A greater void concerns the channel/CaM interfaces postulated by slow CaM and SQS schemes. If we follow the lead of preliminary data, and abandon a prevailing 'IQ-centric' view, where apoCaM and Ca2+/CaM both interact with the IQ domain to trigger channel regulation, little would be known. This indeterminacy obscures the linkage of our promising functional mechanisms to molecular reality, and confounds understanding of just discovered physiological tuning of CaM regulation via RNA editing of CaV channels. These prominent challenges will be addressed by three specific aims. 1) To quantify the Ca2+ dependence of calmodulation via dynamic control of Ca2+ inputs to channels, as afforded by UV Ca2+ uncaging. 2) To identify the molecular states underlying CaM regulation of CaV channels, using an approach termed individually Transformed Langmuir (iTL) analysis, combined with in silico prediction of CaM/channel configurations. 3) To deduce, using Aim 2 insight, the mechanism whereby RNA editing of CaV1.3 channels alters their CaM regulation.

描述（由申请人提供）：钙调蛋白（CAM）对CAV1-2通道的调节，无论是生物学上还是作为一般调节原型，具有鉴别Ca2+解码功能。在较早的周期中，发现CA2+Fre-Fre-Fre-CAM（apocam）与通道内细胞内羧基末端的智商域预先相关。 Ca2+结合该居民CAM会引起某种促进（CDF）或灭活（CDI）通道开口的尚未构象变化，将Calsodut​​ion施放为CA2+的正反馈控制系统。有趣的是，CAM的Ca2+结合CAM的C和N末端裂片各自都会引起不同形式的通道调节形式，从而在Pargarecium中呼应了CAM“功能性两分”的早期发现。更明显的是，C-LOBE对相关通道驱动的〜100毫米Ca2+脉冲的反应（局部CA2+选择性），而N-lobe则能够以某种方式感应来自遥远CA2+源的信号较弱（全球选择性）。在当前周期中，我们以粗略的轮廓推导了CAM的C末端叶（慢速CAM方案）和N末端叶（SQS方案）的钙末次调节功能机制。这些机制解释了这两个镇静调节子系统的显着空间Ca2+解码特性。然而，由于Ca2+通道涌入的复杂性通常会驱动镇定管化的复杂性，因此显着地没有这些低分辨率机械草图的Ca2+依赖性的定量意义。更大的空隙涉及慢速CAM和SQS方案假定的通道/凸轮接口。如果我们遵循初步数据的领导，并放弃了盛行的“以智商为中心”的视图，apocam和ca2+/cam都与智商域进行交互以触发通道调节，那么知之甚少。这种不确定性掩盖了我们有希望的功能机制与分子现实的联系，并通过CAV通道的RNA编辑对CAM调控的刚发现的生理调节混淆了。这些突出的挑战将由三个具体目标解决。 1）通过对Ca2+输入对通道的动态控制来量化CA2+依赖性，如UV Ca2+ Uncing所提供的。 2）使用称为单独转换的langmuir（ITL）分析的方法，识别CAV通道的CAM调节的分子状态，并与CAM/通道构型的计算机预测相结合。 3）使用AIM 2 Insight推断CAV1.3通道的RNA编辑改变其CAM调节的机制。