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What are the probable quaternary structures and biological assemblies?
The assembly pages provide detailed information about probable quaternary structures and biological assemblies that can be generated using crystallographic symmetry information (Figure 29).
Clicking on the images (highlighted in red) will open up an image gallery where only the relevant assembly images are displayed as shown in Figure 30.
![Generation of virus capsid (highlighted in red) for PDB entry 2ws9](https://www.ebi.ac.uk/training/online/courses/exploring-pdb-entry/wp-content/uploads/sites/112/2020/10/assembly1-1024x814.png)
![mage gallery displaying biological assemblies and probable quaternary structures that can be generated based on crystallographic symmetry information](https://www.ebi.ac.uk/training/online/courses/exploring-pdb-entry/wp-content/uploads/sites/112/2020/10/Assembly2-1024x1005.png)
Things to consider:
- The contents of a PDB entry do not always represent the biological assembly
- For X-ray entries, quaternary structures can be generated by expanding the crystal symmetry
- For structures that are not determined by X-ray methods, contents of the PDB entry are likely to represent the biological assembly of the macromolecule
- It is possible to generate more than one quaternary structure by expanding crystal contacts for a particular PDB entry
- Some of these quaternary structures can be stable in the solution and can represent the biological assembly