SAXS TO FOLLOW F-ACTIN DEPOLYMERIZATION BY GELSOLIN

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 涉及细胞形状重排和/或细胞运动的生理功能 要求丝状(F-)肌动蛋白的组装和拆解在空间和时间上发生变化 来自细胞骨架内的单体(球状，G-)肌动蛋白。这个过程是 受到各种肌动蛋白结合蛋白的严格调控，如明胶蛋白，通常作用于 对特定细胞信号的反应，例如细胞内钙离子水平的增加。明胶溶胶剂 肌动蛋白的调节受钙离子和聚磷脂酰肌醇的控制，包括 细丝的切断、封顶和成核。几个研究小组的研究表明 钙离子对明胶蛋白的调节是复杂的，并且在1 在微摩尔范围内，其他的在较高浓度(10？1000微摩尔)被激活。 我们提出的SAXS实验的主要目的是跟踪解聚过程中的结构变化 F-肌动蛋白在明胶存在时的变化及其与钙离子的关系 集中精神。我们建议收集丝状F-肌动蛋白和Factin样本的SAXS数据： 不同摩尔比(1：20到1：1)的明胶：肌动蛋白和5%的明胶复合体 钙浓度水平(0、0.1、1.0、100和1000微摩尔)。这些数据将是 通过典型的SAXS分析工具进行分析，如Porod和Guinier近似、间接 傅里叶变换方法和分子模拟。结果将有助于阐明 明胶解聚肌动蛋白的机理，为 了解肌动蛋白细丝的持续重组是如何由特定的 蛋白质之间的相互作用。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Physiological functions that involve cellular shape rearrangement and/or cellular motility require spatial and temporal changes in the assembly and disassembly of filamentous (F-) actin from pools of monomeric (globular, G-) actin within the cell's cytoskeleton. This process is tightly regulated by various actin-binding proteins, such as gelsolin, which generally act in response to specific cell signals, such as an increase in cellular Ca2+ levels. Gelsolin regulation of actin is under the control of Ca2+ and poly-phosphoinositides and includes severing, capping, and nucleation of filaments. Work from several research groups has shown that Ca2+ regulation of gelsolin is complex and that certain functions are activated in the 1 micromolar range whereas others are activated at higher concentrations (10 ? 1000 micromolar). The main aim of our proposed SAXS experiment is to follow the structural changes during depolymerization of F-actin when in the presence of gelsolin and as a function of Ca2+ concentration. We propose to collect SAXS data on samples of filamentous F-actin and Factin: gelsolin complexes at varying molar ratios (from 1:20 to 1:1) of gelsolin:actin and at 5 levels of calcium concentrations (0, 0.1, 1.0, 100 and 1000 micromolar). These data will be analyzed by typical SAXS analysis tools such as Porod and Guinier approximation, Indirect Fourier Transform methods and molecular modeling. Results will aid in the elucidation of a mechanism for actin de-polymerization by gelsolin, providing a structural basis for understanding how the continuous reorganization of actin filaments is controlled by specific protein-protein interactions.