Watch Exploring Biological Assemblies in the PDBWhen exploring Structure Summary pages, you will notice images and coordinate files for the "Biological Assembly" and the "Asymmetric Unit". In many PDB entries, these are the same. However, for some entries (mostly those solved by X-ray crystallography), you may notice a difference between the asymmetric unit and the biological assembly.
If you have wondered whether the coordinates for the given structure represent the biologically-relevant assembly, watch this virtual office hour to learn more about these terms and how the corresponding data are archived in the files.
For additional information, visit PDB-101's Guide to Understanding PDB Data: Biological Assemblies.