Symmetry Representation in the PDB
An open access article published in the August 2008 issue of Acta Crystallographica Section D describes the new scheme used by the PDB to archive regular non-crystallographic symmetry information for large biological assemblies.
The scheme uses generalized descriptions of deposited and experimental coordinate frames, symmetry and frame transformations. A simple notation encodes the generation of assemblies from deposited coordinates and matrix operations. Complete correct information for building full assemblies, subassemblies and crystal asymmetric units of all virus entries is now available in the remediated PDB archive.