Structural Determinants of the Biological Activity of Ryanodine

ryanodine受体位于肌细胞的三联处，通常作为钙释放通道，将肌膜的去极化与肌浆网的钙释放结合起来，触发肌节收缩。这种受体在其他几种细胞类型中也被发现，但其功能尚不清楚。这种受体之所以如此命名，是因为它能够结合植物生物碱——蛇胺，这种生物碱能稳定开放的通道。该受体在肌肉和其他组织中的广泛分布，以及多种药物调节通道活性的复杂性，强烈表明该受体在细胞功能中的基本作用。目前尚不清楚(a)控制受体通道活性的分子机制是什么，(b)受体在非肌肉细胞中的生理意义，以及(c)是否存在内源性配体与ryanodine位点结合并影响通道。本项目的长期目标是了解ryanodine调节通道活性的分子机制以及受体在完整细胞中的作用。基本策略是结合定向化学合成的ryanodine类似物，测试这些类似物的生物活性，以及基于这些活性的受体分子结构的计算机辅助建模。该项目的具体目标如下：1。合成和测试瑞诺定类似物，以确定确定其激动剂和拮抗剂性质的最小结构因素。绘制已知的高亲和力和低亲和力的ryanodine结合位点，并测试其功能特性。绘制诱导通道打开和关闭状态的结合位点的位点。该项目是四个实验室的持续合作，将在有机合成、膜电生理学、药理学和计算机建模方面贡献专业知识。

The ryanodine receptor, situated in the triad junction of muscle cells, normally functions as the calcium-release channel that couples depolarization of the sarcolemma with calcium release from the sarcoplasmic reticulum to trigger sarcomere contraction. The receptor is also found in several other cell types where its function in not as clear. The receptor is so-named because of its ability to bind the plant alkaloid, ryanodine, which stabilizes the open channel. The wide distribution of the receptor in muscle and other tissues and the complexity by which channel activity is modulated by a variety of agents strongly suggest a fundamental role for the receptor in cellular function. At present it is not known (a)what the molecular mechanisms are that control channel activity of the receptor, (b) the physiological significance of the receptor in non-muscle cells, and (c) whether there are endogenous ligands that bind to the ryanodine site and affect the channel. The long-term goal of this project is to understand the molecular mechanism of ryanodine modulation of channel activity and the role of the receptor in the intact cell. The basic strategy is to combine directed chemical synthesis of ryanodine analogs, the testing of these analogs for their biological activities, and the computer-assisted modeling of the molecular structure of the receptor based on these activities. The specific aims of the project are the following:1. To synthesize and test ryanodine analogs to determine the minimal structural factors that define their agonist and antagonist properties.2. To map the known high and low affinity ryanodine binding sites and to test their functional properties.3. To map those loci of the binding sites that induce the open and closed states of the channel.The project is a continuing collaborative effort of four laboratories, which will contribute expertise in organic synthesis, membrane electrophysiology, pharmacology and computer modeling.