Single-Particle Cryo-Electron Microscopy (Cryo-EM): Progress, Challenges, and Perspectives for Further Improvement

Abstract Electron microscopy (EM) of biological macromolecules has experienced a significant increase in its capabilities with the introduction of a new generation of camera technology. Near-atomic resolution now has been achieved without the need for ordered assemblies such as two-dimensional (2-D) crystals, helical structures, or icosahedral particles. Not only has the resolution achieved in single-particle cryo-electron microscopy (cryo-EM) improved markedly, but at the same time, the number of particles needed has been reduced by a factor of 10 or more. However, not all single-particle analyses may reach atomic resolution easily, and the reasons for this are diverse. Here, we address some of the factors that could result in lower-than-expected values of resolution, and we suggest strategies to identify and fix the possible problems.

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