Cryoelectron Tomography: Visualizing the Molecular Architecture of Cells

Abstract Electron tomography can generate three‐dimensional reconstructions of the macromolecular machinery of the cell in situ with nanoscale resolution. The principles of electron tomography are the same as those applied to the analysis of isolated single complexes. In recent years technological advances have made it possible to apply tomography to ice‐embedded biological material (‘cryotomography’), thereby ensuring a close‐to‐life preservation of the sample. Tomographic reconstruction of biological samples embedded in vitreous ice, combined with advanced computational methods for their interpretation, provides the possibility of comprehensively mapping the macromolecular architecture inside organelles and cells. Thus we can begin to visualize macromolecular machines at work in their natural enviroment.