Electron Microscopic Imaging of Integrin
Rotary-shadowed samples often used for electron microscopy do not preserve native integrin conformations. Negatively stained integrins – or, more desirably, unstained integrins in a cryo-condition – are now being used with sophisticated imaging techniques. Additionally, a single-particle analysis (SPA) of integrins is advanced by the recent determination of several crystal structures of integrins. Nevertheless the conformational flexibility of integrins limits the ability of SPA to image physiologic conformations. To solve this problem, we apply electron tomography to purified integrin, thereby obtaining high-quality three-dimensional (3-D) images that fit well to the atomic structures. We have also taken typical SPA approaches to obtain a 3-D reconstruction of integrin, using conditions that favor the bent conformation.
Key wordsIntegrin Electron microscopy Single-particle analysis Tomography
The author would like to thank Professor Junichi Takagi for critical reading of this manuscript and for his advice, and Emiko Mihara and Naoyuki Miyazaki for technical assistance. A part of this work was supported by “Nanotechnology Network Project of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan” at the Research Center for Ultrahigh Voltage Electron Microscopy, Osaka University (Handai multifunctional Nano-Foundry) and the CREST, JST.
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