The PIR-NRL3D Sequence-Structure Database is produced by PIR-International from sequence and annotation information extracted from three-dimensional structures in the Protein Databank (PDB). The PIR-NRL3D database makes the sequence information in PDB available for similarity searches and retrieval and provides cross-reference information for use with the other PIR Protein Sequence Databases. In constructing PIR-NRL3D, sequence information is extracted only for residues with resolved three-dimensional coordinates (as represented in PDB “ATOM” records) and not for residues that are structurally undefined.

The titles, biological sources, and keywords of the entries are modified to conform to the nomenclature standards used in the other PIR Protein Sequence Databases. All the bibliographic references in the PDB entries are included and many appear with the reference numbers and MEDLINE cross-references they have in corresponding PIR entries. Information from the PDB entries on experimental methods, resolution, and R-factor is included whenever possible. Secondary structure, active site, binding site, and modified site annotations in PDB appear in their corresponding PIR feature formats.