Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
Curr Opin Struct Biol. 2013 Apr;23(2):261-7. doi: 10.1016/j.sbi.2013.02.003. Epub 2013 Mar 4.
Cryo-electron tomography provides low-resolution 3D views of cells, organelles, or viruses. Macromolecular complexes present in multiple copies can be subsequently identified within the 3D reconstruction (the tomogram), computationally extracted, and averaged to obtain higher resolution 3D structures, as well as a map of their spatial distribution. This method, called subtomogram averaging or subvolume averaging, allows structures of macromolecular complexes to be resolved in situ. Recent applications have provided in situ structural data at resolutions of 2-4 nm on samples including polysomes, nuclear pores, vesicle coats, and viral surface proteins. Here I describe the method and discuss limitations, advances and recent applications. I speculate how the method will solve more structures at higher resolution, allowing in situ structural biology.
冷冻电子断层扫描技术提供了细胞、细胞器或病毒的低分辨率 3D 视图。可以在 3D 重建（断层图像）中随后识别多个拷贝存在的大分子复合物，通过计算提取并平均化以获得更高分辨率的 3D 结构以及它们的空间分布图谱。这种方法称为亚断层图像平均或子体积平均，允许原位解析大分子复合物的结构。最近的应用在包括多核糖体、核孔、囊泡外壳和病毒表面蛋白在内的样本中提供了分辨率为 2-4nm 的原位结构数据。在这里，我将描述该方法并讨论其局限性、进展和最近的应用。我推测该方法将如何以更高的分辨率解决更多的结构问题，从而实现原位结构生物学。
