The BLAST Databases
Last updated on July 21, 2003
This document describes the "BLAST" databases available on the NCBI
FTP site under the "blast/db" subdirectory. The direct URL to this
subdirectory is:
ftp://ftp.ncbi.nih.gov/blast/db
I. General Introduction
NCBI BLAST home pages (http://www.ncbi.nih.gov/BLAST/) use a standard
set of BLAST databases for Nucleotide, Protein, and Translated BLAST
searches. These databases are made available in the db directory as
compressed archives (ftp://ftp.ncbi.nih.gov/blast/db/) in preformatted
format. The FASTA databases now reside under the blast/FASTA
subdirectory.
The preformatted databases offer the following advantages:
* The preformatted databases are smaller in size and are
faster to download;
* Preformatting removes the need to run formatdb;
* Taxonomy information is available for each database entry.
Preformatted databases must be downloaded in binary mode and inflated
with gzip or other decompress tools. The BLAST database files can then
be extracted out of the resulting tar file using “tar” program on Unix/Linux
or WinZip and StuffIt Expander on Windows and Macintosh platforms,
respectively.
Large databases are formatted in multiple 1 Gigabytes volumes, which
are named using the “database.##.tar.gz” convention. All relevant volumes
are required. An alias file is provided so that the database can be called
using the alias name without the extension (.nal or .pal). For example,
to call est database, simply use “–d est” option in the commandline
(without the quotes).
Certain databases are subsets of a larger parental database. For those
databases, mask files, rather than actual databases, are provided. The
mask file needs the parent database to function properly. The parent
databases should be generated on the same day as the mask file. For
example, to use swissprot preformatted database, swissprot.tar.gz, one
will need to get the nr.tar.gz with the same date stamp.
Additional BLAST databases that are not provided in preformatted
formats are available in the FASTA subdirectory. For genomic BLAST
databases, please check the genomes ftp directory at:
ftp://ftp.ncbi.nih.gov/genomes/
2. Contents of the /blast/db/ directory
The formatted databases are archived in this directory. The name of
these databases and their contents are listed below.
+--------------------+-----------------------------------------------+
|File Name | Content Description |
+--------------------+-----------------------------------------------+
/FASTA subdirectory for FASTA formatted sequences
README README for this subdirectory (this file)
est.00.tar.gz | three volumes of the formatted est database
est.01.tar.gz | from the EST division of GenBank, EMBL,
est.02.tar.gz | and DDBJ
est_human.tar.gz | mask file for human subset of the est
est_mouse.tar.gz | mask file for mouse subset of the est
est_others.tar.gz | mask file for non-human and non-mouse subset
| of the est database
| These three mask files need all volumes of
| est to function properly.
gss.00.tar.gz | two volumes of the formatted gss database
gss.01.tar.gz | from the GSS division of GenBank, EMBL, and
| DDBJ
htgs.00.tar.gz | three volumes of htgs database with entries
htgs.01.tar.gz | from HTG division of GenBank, EMBL, and DDBJ
htgs.01.tar.gz |
human_genomic.tar.gz human RefSeq (NC_######) chromosome records
with gap adjusted concatenated NT_ contigs
nr.tar.gz non-redundant protein sequence database with
entries from GenPept, Swissprot, PIR, PDF, PDB,
and NCBI RefSeq
nt.00.tar.gz | nucleotide sequence database, with entries
nt.01.tar.gz | from all traditional divisions of GenBank,
nt.02.tar.gz | EMBL, and DDBJ excluding bulk divisions (gss,
| sts, pat, est, and htg divisions. wgs entries
| are also excluded. Not non-redundant.
other_genomic.tar.gz RefSeq chromosome records (NC_######) for
organisms other than human
pataa.tar.gz | patent protein sequence database
patnt.tar.gz | patent nucleotide sequence database
| The above two databases are directly from
| USPTO or from EU/Japan Patent Agencies via
| EMBL/DDBJ
pdbaa.tar.gz protein sequences from pdb protein structures
pdbnt.tar.gz nucleotide sequences from pdb nucleic acid
structures. They are NOT the protein coding
sequences for the corresponding pdbaa entries.
sts.tar.gz Sequences from the STS division of GenBank, EMBL,
and DDBJ
swissprot.tar.gz swiss-prot sequence databases (last major update)
taxdb.tar.gz Taxonomy information for the formatted database
wgs.00.tar.gz | Whole genome shotgun sequence assemblies for
wgs.01.tar.gz | different organisms, broken up into 1 GB
wgs.02.tar.gz | volumes.
wgs.03.tar.gz
wgs.04.tar.gz
wgs.05.tar.gz
+--------------------+-----------------------------------------------+
3. Content of the /db/FASTA Subdirectory
This subdirectory contains FASTA formatted sequence files, formerly
available under /db directory. The file names and database contents
are listed below. These files are now archived in .gz format and must
be processed through formatdb before they can be used by the BLAST
programs.
+--------------------+-----------------------------------------------+
|File Name | Content Description |
+--------------------+-----------------------------------------------+
alu.a.gz translation of alu.n repeats
alu.n.gz alu repeat elements
drosoph.aa.gz CDS translations from drosophila.nt
drosoph.nt.gz genomic sequences for drosophila
ecoli.aa.gz CDS translations from ecoli.nt
ecoli.nt.gz Escherichia coli K-12 genomic sequences
est_human.gz* | human subset of the est database (see Note 1)
est_mouse.gz* | mouse subset of the est database
est_others.gz* | non-human and non-mouse subset of the est
database
gss.gz* sequences from the GSS division of GenBank,
EMBL, and DDBJ
htg.gz* htgs database with high throughput genomic
entries from the htg division of GenBank,
EMBL, and DDBJ
human_genomic.gz* human RefSeq (NC_######) chromosome records
with gap adjusted concatenated NT_ contigs
igSeqNt.gz human and mouse immunoglobulin nucleotide
sequences
igSeqProt.gz human and mouse immunoglobulin protein
sequences
mito.aa.gz CDS translations of complete mitochondrial
genomes
mito.nt.gz complete mitochondrial genomes
month.aa.gz | newly released/updated protein sequences
(See Note 2)
month.est_human.gz | newly released/updated human est sequences
month.est_mouse.gz | newly released/updated mouse est sequences
month.est_others.gz | newly released/updated est other than
| human/mouse
month.gss.gz | newly released/updated gss sequences
month.htgs.gz | newly released/updated htgs sequences
month.nt.gz | newly released/updated sequences for the nt
database
nr.gz* non-redundant protein sequence database with
entries from GenPept, Swissprot, PIR, PDF,
PDB, and RefSeq
nt.gz* nucleotide sequence database, with entries
from all traditional divisions of GenBank,
EMBL, and DDBJ excluding bulk divisions
(gss, sts, pat, est, htg divisions) and wgs
entries. Not non-redundant.
other_genomic.gz* RefSeq chromosome records (NC_######) for
organisms other than human
pataa.gz* | patent protein sequence database
patnt.gz* | patent nucleotide sequence database
| The above two dbs are directly from USPTO
| of from EU/Japan Patent Agency via EMBL/DDBJ
pdbaa.gz* protein sequences from pdb protein structures
pdbnt.gz* nucleotide sequences from pdb nucleic acid
structures. They are NOT the protein coding
sequences for the corresponding pdbaa entries.
sts.gz* database for sequence tag site entries
swissprot.gz* swiss-prot database (last major release)
vector.gz vector sequence database (See Note 3)
wgs.gz* whole genome shotgun genome assemblies
yeast.aa.gz protein translations from yeast genome
yeast.nt.gz yeast genomes.
+--------------------+-----------------------------------------------+
NOTE:
(1) we do not provide the complete est database in FASTA format. One
need to get all three subsets(est_human, est_mouse, and est_others
and concatenate them into the complete est fasta database.
(2) month.### databases are the sequences newly released or updated
within the last 30 days for that database.
(3) For vector contamination screening, use the UniVec database from:
ftp://ftp.ncbi.nih.gov/pub/UniVec/
* marked files have preformatted counterparts.
4. Database updates
The BLAST databases are updated daily. Update of existing databases
by merging of new records from the month database using fmerge is no
longer supported. We do not have an established incremental update
scheme at this time. We recommend downloading the databases regularly
to keep their content current.
5. Non-redundant defline syntax
The only non-redundant database is the protein nr. In it, identical
sequences are merged into one entry. To be merged two sequences must
have identical lengths and every residue at every position must be the
same. The FASTA deflines for the different entries that belong to one
nr record are separated by control-A characters invisible to most
programs. In the example below both entries gi|1469284 and gi|1477453
have the same sequence, in every respect:
>gi|3023276|sp|Q57293|AFUC_ACTPL Ferric transport ATP-binding protein afuC
^Agi|1469284|gb|AAB05030.1| afuC gene product ^Agi|1477453|gb|AAB17216.1|
afuC [Actinobacillus pleuropneumoniae]
MNNDFLVLKNITKSFGKATVIDNLDLVIKRGTMVTLLGPSGCGKTTVLRLVAGLENPTSGQIFIDGEDVT
KSSIQNRDICIVFQSYALFPHMSIGDNVGYGLRMQGVSNEERKQRVKEALELVDLAGFADRFVDQISGGQ
QQRVALARALVLKPKVLILDEPLSNLDANLRRSMREKIRELQQRLGITSLYVTHDQTEAFAVSDEVIVMN
KGTIMQKARQKIFIYDRILYSLRNFMGESTICDGNLNQGTVSIGDYRFPLHNAADFSVADGACLVGVRPE
AIRLTATGETSQRCQIKSAVYMGNHWEIVANWNGKDVLINANPDQFDPDATKAFIHFTEQGIFLLNKE
The syntax of sequence header lines used by the NCBI BLAST server
depends on the database from which each sequence was obtained. The table
below lists the identifiers for the databases from which the sequences
were derived.
Database Name Identifier Syntax
============================ ========================
GenBank gb|accession|locus
EMBL Data Library emb|accession|locus
DDBJ, DNA Database of Japan dbj|accession|locus
NBRF PIR pir||entry
Protein Research Foundation prf||name
SWISS-PROT sp|accession|entry name
Brookhaven Protein Data Bank pdb|entry|chain
Patents pat|country|number
GenInfo Backbone Id bbs|number
General database identifier gnl|database|identifier
NCBI Reference Sequence ref|accession|locus
Local Sequence identifier lcl|identifier
"gi" identifiers are being assigned by NCBI for all sequences contained
within NCBI's sequence databases. The "gi" identifier provides a uniform
and stable naming convention whereby a specific sequence is assigned its
unique gi identifier. If a nucleotide or protein sequence changes,
however, a new gi identifier is assigned, even if the accession number
of the record remains unchanged. Thus gi identifiers provide a mechanism
for identifying the exact sequence that was used or retrieved in a given
search.
We recommend that "gi display option" be activated in local blast search
by setting the -I option to T, which was set to false by default:
-I Show GI's in deflines [T/F]
default = F
For databases whose entries are not from official NCBI sequence databases,
such as Trace database, the gnl| convention is used. For custom database,
this convention should be followed and the id for each sequence must be
unique, if one would like to take the advantage of indexed database,
which enables specific sequence retrieval using fastacmd program included
in the blast executable package. One should refer to documents
distributed in the standalone BLAST package for more details.
6. Formatting the FASTA database
FASTA database files need to be formatted with formatdb before they can be
used in local blast search. For those from NCBI, the following formatdb
are recommended:
formatdb –i input_db –p F –o T for nucleotide
formatdb –i input_db –p T –o T for protein
The -A option introduced in 2.2.3 is now built into the formatdb program
and thus removed from the list of configurable options since 2.2.8. This
enables formatdb to properly handle large sequence files (longer than 16
million bases). Please refer to formatdb.txt under the /blast/documents
directory for more information. Database preprared using 2.2.8 formatdb
will not be backward compatible with blast programs old than version 2.2.3.
7. Technical Support
Questions and comments on this document and NCBI BLAST related questions
should be sent to blast-help group at:
blast-help@ncbi.nlm.nih.gov
For information about other NCBI resources/services, please send email to
NCBI User Serivce at:
info@ncbi.nlm.nih.gov