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![[Figure 1]](me6053fig1mag.jpg)
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Figure 1
(a) X-ray crystallography electron-density map: SeMet (selenomethionine) MAD (multiple-wavelength anomalous dispersion), phased at 2.5 Å resolution (translation initiation factor 2, IF2; PDB ID 4b3x; Simonetti et al., 2013  ). Note the histidine residue defined by the map. (b) Cryo-EM map: obtained by 3D reconstruction from individual 2D particle images (60S ribosomal subunit of the 80S human ribosome, 2.9 Å average resolution with local resolution extending this; Natchiar et al., 2017a). Note the histidine residues defined by the map (to be compared with panel a) and the nucleotides in the vicinity. (c) Increasing number of cryo-EM maps deposited in the EMDB and achieving the specified resolution levels. The data are taken from the https://www.ebi.ac.uk/pdbe/emdb/ and https://www.rcsb.org/pdb/ websites [updated graph compared with the one shown in Orlov et al. (2017) as of 26 September 2016, within the shaded light pink box; and as of 20 September 2019], illustrating an over fivefold increase in cryo-EM structures at high resolution (4 Å or better, red curve) within the last three years. The black arrow marks the year 2013 where high-sensitivity detectors entered the cryo-EM field. (d) Graph showing the PDB data distribution by molecular weight. While most structures lie below 60 kDa and are determined by X-ray crystallography, those at high molecular weight (right-hand end) are more amenable to cryo-EM, although complexes in the 50–150 kDa range can now be targetted by cryo-EM as well. (e) Graph from Liebschner et al. (2019) in this issue, illustrating that since 2015, cryo-EM depositions have accounted for the majority of large macromolecular structures currently in the PDB. |
![[Figure 1]](me6053fig1.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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