Protein Data Bank
The World Wide Protein Data Bank (wwPDB) is the internationally recognized sole repository of all published, empirically-determined macromolecular three-dimensional (3D) structure data. In 2008, it has three official branches: the Research Collaboratory for Structural Bioinformatics (USA), the European Bioinformatics Institute (UK), and the Protein Data Bank Japan.
Many derivative databases copy, derive information from, or add value to the atomic coordinate files available from the wwPDB.
For more information, please see the Protein Data Bank in Wikipedia.