To improve the clarity of assembly definitions in curation, wwPDB now makes curated PDB assemblies available for depositors to view in OneDep using the Mol* viewer. One of the important processes in curation of PDB entries is the definition of assemblies for each structure. This helps users of PDB data to understand the structure in the context of its complex formation in the specific experimental conditions. To ensure that assemblies are curated correctly, they are reviewed by annotators at the time of curation before being reported back to the depositors after the curation process. The deposition system in OneDep has now been enhanced so that after curation, the annotated assembly is displayed in the Mol* 3D viewer <https://molstar.org/> for depositors to review. This viewer is available in a new Review section in the deposition interface, which is present after curation of the entry. The Mol* viewer can display PDB structure data within the browser with minimal memory requirements, therefore making it quick and easy to visually display assembly information. These changes will help improve the validation and reporting of curated assemblies during the deposition process. The assembly review page, as displayed for depositors after curation of the entry. The curated assembly is displayed in the Mol* 3D viewer, within the browser. The assembly review page, as displayed for depositors after curation of the entry. The curated assembly is displayed in the Mol* 3D viewer, within the browser. <http://www.wwpdb.org/news/news?year=2021#top>