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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Mechanistic basis of bell-shaped dependence of inositol 1,4,5-trisphosphate receptor gating on cytosolic calcium
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Mechanistic basis of bell-shaped dependence of inositol 1,4,5-trisphosphate receptor gating on cytosolic calcium

机译：1，4，5-三磷酸肌醇受体门控钟形依赖于胞质钙的机制基础

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摘要

The inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) is an intracel-lular Ca2+ release channel, and its opening is controlled by IP3 and Ca2+. A single IP3 binding site and multiple Ca2+ binding sites exist on single subunits, but the precise nature of the interplay between these two ligands in regulating biphasic dependence of channel activity on cytosolic Ca2+ is unknown. In this study, we visualized conformational changes in IP3R evoked by various concentrations of ligands by using the FRET between two fluorescent proteins fused to the N terminus of individual subunits. IP3 and Ca2+ have opposite effects on the FRET'signal change, but the combined effect of these ligands is not a simple summative response. The bell-shaped Ca2+ dependence of FRET efficiency was observed after the subtraction of the component corresponding to the FRET change evoked by Ca2+ alone from the FRET changes evoked by both ligands together. A mutant IP3R containing a single amino acid substitution at K508, which is critical for IP3 binding, did not exhibit this bell-shaped Ca2+ dependence of the subtracted fRET efficiency. Mutation at E2100, which is known as a Ca2+ sensor, resulted in ~ 10-fold reduction in the Ca2+ dependence of the subtracted signal. These results Suggest that the subtracted FRET signal reflects IP3R activity. We propose a five-state model, which implements a dual-ligand competition response without complex allosteric regulation of Ca2+ binding affinity, as the mechanism underlying the IP3-dependent regulation of the bell-shaped relationship between the IP3R activity and cytosolic Ca2+.
机译：肌醇1,4,5-三磷酸（IP3）受体（IP3R）是细胞内Ca2 +释放通道，其开放受IP3和Ca2 +控制。在单个亚基上存在单个IP3结合位点和多个Ca2 +结合位点，但尚不清楚这两个配体之间相互作用调节通道活性对胞质Ca2 +的双相依赖性的确切性质。在这项研究中，我们通过使用两个与单个亚基N端融合的荧光蛋白之间的FRET可视化了各种浓度的配体引起的IP3R构象变化。 IP3和Ca2 +对FRET的信号变化具有相反的影响，但是这些配体的综合作用并不是简单的累加响应。从两个配体共同引起的FRET变化减去与单独由Ca2 +引起的FRET变化相对应的成分后，观察到了FRET效率的钟形Ca2 +依赖性。突变IP3R在K508处包含单个氨基酸取代，这对IP3结合至关重要，但没有表现出这种钟形的Ca2 +依赖于所减去的fRET效率。 E2100处的突变（称为Ca2 +传感器）导致所减去信号对Ca2 +的依赖性降低了约10倍。这些结果表明减去的FRET信号反映了IP3R活动。我们提出了一种五态模型，该模型无需对Ca2 +结合亲和力进行复杂的变构调节即可实现双配体竞争反应，作为IP3R活性与胞质Ca2 +之间钟形关系的IP3依赖调节基础的机制。

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    Tadashi Shinohara; Takayuki Michikawa; Masahiro Enomoto; Jun-lchi Goto; Miwako lwai; Toru Matsu-ura; Haruka Yamazaki; Akitoshi Miyamoto; Akio Suzuki; Katsuhiko Mikoshiba;

  • 作者单位

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan;

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan,Calcium Oscillation Project, International Cooperative Research Project and Solution-Oriented Research for Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan;

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan;

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan;

    Division of Molecular Pathology, Department of Cancer Biology;

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan;

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan;

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan,Division of Neuronal Network, Department of Basic Medical Sciences, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639, Japan;

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan;

    Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, Wako, Saitama 351-0198, Japan,Calcium Oscillation Project, International Cooperative Research Project and Solution-Oriented Research for Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    calcium signal; channel gating; ion channel;

    机译：钙信号;通道门控;离子通道;

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