Measuring local-directional resolution and local anisotropy in cryo-EM maps

By incorporating directionality, to the already common local resolution, in different parts of a specimen 3D map, we can estimate how reliable is the local information differentiating among all possible directions. This approach allows estimating the quality of a cryoEM map without the need of original images and opens new ways for model tracing and for sharpening and enhancing the maps.
Vilas JL, Tagare HD, Vargas J, Carazo JM, Sorzano COS.
Nat Commun 2020 Jan; 11: 55.
The introduction of local resolution has enormously helped the understanding of cryo-EM maps. Still, for any given pixel it is a global, aggregated value, that makes impossible the individual analysis of the contribution of the different projection directions. We introduce MonoDir, a fully automatic, parameter-free method that, starting only from the final cryo-EM map, decomposes local resolution into the different projection directions, providing a detailed level of analysis of the final map. Many applications of directional local resolution are possible, and we concentrate here on map quality and validation.
PubMed: 31896756. Doi: 10.1038/s41467-019-13742-w. OPEN Free PMC