The resolution in Cryo-EM is not based on the direct observation of the raw data. The numerical value highly depends on the data processing methods. The most commonly used criterion, Fourier Shell Correlation (FSC), reflects the self-consistency of the data, not the actual quality of the EM density map. The bottom-line is never taking the FSC at face value. A resolution claim has to be backed by visual inspection of the density map and comparison with other structures solved at similar resolutions.
In-depth reading:
- Optimal Determination of Particle Orientation, Absolute Hand, and Contrast Loss in Single-particle Electron Cryomicroscopy
- High-resolution noise substitution to measure overfitting and validate resolution in 3D structure determination by single particle electron cryomicroscopy
- ‘Atomic resolution’: a badly abused term in structural biology
- Addressing preferred specimen orientation in single-particle cryo-EM through tilting