The asymmetric unit is used by the crystallographer to refine the structure against experimental data and does not necessarily represent a biologically functional molecule.
An asymmetric unit may contain:
Hemoglobin, a molecule with four protein chains (two alpha-beta dimers), provides a good example of each of these cases:
You can reach the Structure Summary Page of each asymmetric unit by typing the corresponding PDB code in the search (blue) bar on the PDB home pageor you can simply click on the PDB codes in the table above.
Return to CAB Home