GenBank Accession Number Reference Sheet: The International Nucleotide Sequence Database Collaboration (INSDC) consists of the DNA DataBank of Japan (DDBJ), the European Molecular Biology Laboratory (EMBL) and GenBank at NCBI. As part of the Collaboration, all three organizations accept new sequence submissions and share sequence data among the three databases. To facilitate the exchange of data, each member of the collaboration is assigned certain accession prefixes. In addition to the accession number, GenBank records also have a GI number. The GI number is simply a series of digits assigned consecutively to sequences submitted to NCBI. Format of GenBank accession numbers: Type Format Nucleotide 1 letter + 5 numbers or 2 letters + 6 numbers Protein 3 letters + 5 numbers WGS 4 letters + 2 numbers for WGS assembly version + 6-8 numerals Primary GenBank accession number prefixes: Prefixes Data Source AE, CP, CY Genome projects (nucleotide) U, AF, AY, DQ Direct submissions (nucleotide) AAAA-AZZZ Whole genome shotgun sequences (nucleotide) AAA-AZZ Protein ID EAA-EZZ WGS protein ID O, P, Q Swissprot (protein) Version number suffix: GenBank sequence identifiers consist of an accession number of the record followed by a dot and a version number (i.e. accession.version). The version number is incremented whenever the sequence record is updated. Refseq Accession Format: Refseq accession numbers do not follow the standards set by INSDC. It has a distinct format of 2 letters + underbar + 6 digits (i.e. NM_012345). Refseq records can either be curated (manually reviewed by NCBI staff or collaborators) or automated (records not individually reviewed). Prefixes Molecule Method NC, NG Genomic Curated NM MRNA Curated NR RNA Curated NP Protein Curated NT, NW Genomic Automated XM MRNA Automated XR RNA Automated XP Protein Automated The complete list of accession numbers is available at http://www.ncbi.nlm.nih.gov/Sequin/acc.html. .