Heat map showing how (X-ray-determined) Protein Data Bank (PDB) entries trend with data resolution and molecular weight. There are many structures recorded between 1.5 and 2.5 Å resolution with a molecular weight of around 40 kDa, indicated by a lighter color. The white dots represent the mean average resolutions for structures in 10 kDa ranges. This figure shows that larger molecules tend to have poorer resolutions. As the molecular weight of structures increases, the mean resolution of the recorded X-ray data also increases. The PDB only contains structures that have been finalized; therefore, there may be many more low-resolution data sets from crystals that did not yield publication-quality structures.