Proteins databank accession numbers

A number of structural databases have been developed to classify proteins accoi dmg to their three-dimensional structures. Many of these are accessible via the World Wide Web. The protein databank (PDB [Bernstein t f al. 1977]) is the primary source of data about the structures of biological macromolecules and contains a large number of structures, but many of these are of identical proteins (complexed with different ligands or determined at different resolutions) or are of close homologues. 

There are increasing numbers of protein sequences available as a result of the increasing numbers of genome sequences that are now accessible in public databanks. It is estimated that there were experimentally determined structures for 1% of the protein sequences known in 1999, meaning that inferences about structure had to rely on information from models for the remaining 99%. 

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