Database Sequence Identifier

Sequence datas from various sources are collected in computation biology library. Research would be of no use when it cannot be retrieved during the time of requirement. The ways by which sequence can be obtained is formulated by National Center for Biotechnology Institute (NCBI).  Accession number helps in easy retrieval but, then every database like GenBank, SWISSPOR, EMBL and DDBJ have their own accession numbers. 

Locus name

This is a unique identifier for each database. It incorporates the function of locus and source from which sequence is computed. This helps the retriever to obtain the datas easily. It is represented as ID in EMBL database, LOCUS in DDBJ and GenBank database. The number of sequence and source organism increases over the years; database fails to meet the statutory laid by NCBI.

Accession number

To overcome the difficulty of database maintenance of unique identifier or Locus name, accession number was introduced by International Nucleotide Sequence Database Collaborators. It includes one alpha letter followed by 5 digit numbers. Later, new accession number consists of two alpha letters followed by  6 digit numbers  in which the first letter corresponds to database collaborator for, it be unique. They are stable over a period of years but changes as it includes the whole database records. When the database is not updated, it creates indifference problems. It is represented as ACCESSION  in GenBank database.

gi Number

gi Number, GenInfo identifier was introduced by NCBI in the year 1992. It is assigned in addition to accession number. It is represented as an integer and is unique for each database to find a particular sequence. It is stable over a period of time and can be retrieved at any moment.

Accession version combined identifier

The combination of accession number with version number is referred as accession version combined identifier. If the user is not aware of the version, then the sequence of latest version can be retrieved. It is represented as VERSION in GenBank database.