How molecular sequences are linked to experimentally observed atoms.

The blue-boxes are regions for which atoms records are available. For the grey regions there is sequence information available in the PDB, but no coordinates.

The sequence that has been used in the experiment is stored in the **Seqres** records in the PDB. It is often not the same sequences as can be found in Uniprot, since it can contain cloning-artefacts and modifications that were necessary in order to crystallize a structure.

By default BioJava loads both the Seqres and Atom groups into the [Chain](http://www.biojava.org/docs/api/org/biojava/nbio/structure/Chain.html)

objects.

Groups that are part of the Seqres sequence as well as of the Atom records are mapped onto each other. This means you

can iterate over all Seqres groups in a chain and check, if they have observed atoms.

The mapping between PDB and UniProt changes over time, due to the dynamic nature of biological data. The [PDBe](http://www.pdbe.org) has a project that provides up-to-date mappings between the two databases, the [SIFTs](http://www.ebi.ac.uk/pdbe/docs/sifts/) project.

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| Chapter 7 : SEQRES and ATOM records

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