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跨膜结构域对钙膜相互作用的影响
Influence of a transmembrane domain on calcium-membrane interaction |
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| 课程网址: |
http://videolectures.net/biophysics2018_melcrova_calcium_membrane...
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| 主讲教师: |
Adela Melcrova
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| 开课单位: |
捷克共和国科学院
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| 开课时间: |
2018-07-09
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| 课程语种: |
英语
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| 中文简介: |
钙在包括细胞信号传导或膜融合在内的各种细胞过程中起着重要作用。钙离子与质膜（PM）带负电的内部小叶有很强的相互作用，质膜是许多信号通路的目标分子。最近研究了钙结合后磷脂膜的生物物理特性的变化（1）。我们通过整合跨膜肽，进一步了解了钙与PM的生物学相关模型的结合，从而迈出了又一步。我们将肽设计为单个跨膜螺旋，总电荷为零或有少量正电荷。带正电荷的肽遵循所谓的正内部规则，该规则规定螺旋TM蛋白的过量正电荷位于PM的细胞质侧。然而，预期带正电荷会排斥钙离子。我们使用时间分辨发射光谱法对脂质囊泡进行zeta电位测量。荧光技术为我们提供了有关荧光探针附近分子的水合和迁移率的信息，而zeta电位则显示了所研究膜表面电荷的趋势。我们发现，两种跨膜肽的确可以使磷脂双层硬化。正电荷只会增强这种效果。出乎意料的是，无论肽的含量如何，该肽的正电荷都不会影响钙与膜的结合。
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| 课程简介: |
Calcium plays a significant role in various cellular processes including cell signaling or membrane fusion. Calcium ions have strong interactions with the negatively charged inner leaflet of plasma membrane (PM) where are the target molecules of many signaling pathways. Changes in biophysical properties of phospholipid membranes upon calcium binding were recently investigated (1). We took another step in further understanding the calcium binding to biologically relevant model of PM by incorporating a transmembrane peptide. We designed the peptide as a single transmembrane helix with either zero total charge or with a mild amount of positive charge. The positively charged peptide follows the so called positive-inside rule stating that the excess positive charge of helical TM proteins resides at the cytoplasmic side of the PM. The positive charge is however expected to repel the calcium ions. We use time-resolved emission spectroscopy of lipid vesicles accompanied by zeta potential measurements. The fluorescence technique gives us information on hydration and mobility of molecules in the vicinity of a fluorescent probe whereas the zeta potential shows trends in surface charge on the studied membranes. We found out that both transmembrane peptides indeed rigidify phospholipid bilayers. The positive charge only strenghtens this effect. Surprisingly, the positive charge of the peptide has no influence on calcium binding to membranes which is the same regardless the peptide content.
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| 关 键 词: |
钙离子; 跨膜肽; 时间分辨发射光谱法
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| 课程来源: |
视频讲座网
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| 数据采集: |
2020-11-22：cjy
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| 最后编审: |
2020-11-22：cjy
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| 阅读次数: |
65
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