In situ visualizing T-Tubule/SR junction reveals the ultra-structures of calcium storage and release machinery

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• 作者：XiaoWei Song¹ ; Ying Tang¹ ; ChangHai Lei¹ ; Mi Cao ; YaFeng Shen ; YongJi Yang ; ^{yangyj22@smmu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Integral&ndash ; integral-membrane proteins ; RyR1 ; Macromolecular architecture ; Electron tomography ; DHPR
• 刊名：International Journal of Biological Macromolecules
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：82
• 期：Complete
• 页码：7-12
• 全文大小：2096 K

文摘

In skeletal muscle, Ca²⁺ release from sarcoplasmic reticulum (SR) following the action potential relies on the delicate architecture of the T-Tubule/SR junction. The T-Tubule/SR junction comprises two membrane systems: the integral proteins DHPR and RyR1 and the Ca²⁺-buffering apparatus within the SR lumen. The arrangement and interactions of the components have remained elusive due to technological limitations. Here, we determined whether electron tomography is effective fort the in situ determination of the relationships between RyR1 and DHPR, the SR membrane and other involved structures. First, we visually confirmed that RyR1 and DHPR are close neighbors that are mutually staggered with each other and directly interact with one of RyR1 subunits. Second, the Ca²⁺ storage network within the SR lumen is directly correlated with RyR1. These results suggest that the excitation of the T-Tubule may induce Ca²⁺ release through a direct interaction among DHPR, RyR1 and the Ca²⁺ buffering apparatus. These results indicate that electron tomography has potential as an efficient method for the in situ characterization of the complex architecture and arrangement of two integral–integral-membrane proteins in the context of the surrounding phospholipid-bilayer and proteins.