Protein identifier types and reachability. This figure provides the availability of accession types for proteins found in iRefIndex version 8.0. There were 86,757 ROGIDs which refer to unique primary amino sequence and NCBI taxonomy identifier combinations. Out of these, only 82.1% can be directly mapped to a UniProt/KB accession. Thus there were 15, 561 ROGIDs that could not be mapped to a UniProt/KB. Out of the 15,561 that could not be mapped to a UniProt/KB, 9,928 could not be mapped to a RefSeq accession either. Of the 11.5% of proteins in iRefIndex that could not be mapped to a UniProt or a RefSeq accession 5,409 had PDB identifiers. Finally 4,519 ROGIDs (5.2% of all ROGIDs) were not reachable using queries with any of these accession types but could be found using ROGIDs or other accession type searches.