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UniProt release 4.0

Published February 1, 2005


UniProtKB/Swiss-Prot major release (51.0)

Release 46.0 of Swiss-Prot contains 168'297 sequence entries, comprising 61'443'278 amino acids abstracted from 124'910 references.

4'537 sequences have been added since release 45, the sequence data of 866 existing entries has been updated and the annotations of 77'494 entries have been revised. This represents an increase of 3%.

Many improvements were carried out in the last 3 months. In particular, we have extended the format for ID lines in both Swiss-Prot and TrEMBL.

UniProt Knowledgebase release 4.0 includes Swiss-Prot release 46.0 and TrEMBL release 29.0.

Full statistics and release notes

UniProtKB News

Modification to the ftp server directory structure

In order to provide access to the last major Swiss-Prot and TrEMBL releases (as opposed to the biweekly releases) via the UniProt ftp servers,, and, we changed the directory structure of our ftp sites.

In addition to the possibility of downloading the complete databases, we provide the data in the form of taxonomic divisions for archaea, bacteria, fungi, human, invertebrates, mammals, plants, rodents, vertebrates, viruses and unclassified.

The new structure will be:

Symbolic links will be established for the following existing directories:
/databases/uniprot/knowledgebase to 
/databases/uniprot/uniref        to 

On and
/databases/swiss-prot/release_compressed to
/databases/trembl/release_compressed     to

The directory on ExPASy that used to contain uncompressed Swiss-Prot releases, /databases/swiss-prot/release/, will be removed.

Please note that if you are interested in complete proteomes, you can download:

Extension of the TrEMBL entry name format

Previously, TrEMBL used the accession number as the entry name. With this release, TrEMBL entry names are composed of the accession number and organism identification codes (O95417_HUMAN, Q9VVG0_DROME, P71025_BACSU, Q9SR52_ARATH, etc.). The speclist.txt file lists the organism identification codes which are used to build the "organism" part of an entry name in Swiss-Prot. This file has been extended to include codes to be used in TrEMBL. As it is not possible in a reasonable timeframe to manually assign organism codes to all species represented in TrEMBL, it was decided to define "virtual" codes that regroup organisms at a certain taxonomic level. Such codes are prefixed by the number "9" and generally correspond to a "pool" of organisms which can be 'wide' as a kingdom. Here are some examples of such codes:

9BACT B      2: N=Bacteria
9CNID E   6073: N=Cnidaria
9FUNG E   4751: N=Fungi
9REOV V  10880: N=Reoviridae
9TETR E  32523: N=Tetrapoda
9VIRI E  33090: N=Viridiplantae

TrEMBL entries are widely used for sequence analysis such as similarity search, multiple sequence alignments or phylogenetic analysis. The extension of the entry name will simplify the species identification in the analysis results.

Change of the entry name in many Swiss-Prot entries

In the last release we introduced to Swiss-Prot the first entry with the new format of the entry name. With this release, many entry names have changed to the new format.

New comment line (CC) topic: INTERACTION

The CC line topic INTERACTION is used to convey information relevant to binary protein-protein interactions. It is automatically derived from the IntAct database and is updated on a monthly basis. The occurrence is one INTERACTION topic per entry, with each binary interaction being presented in a separate line. Each data line can be longer than 75 characters.

Interactions can be derived by any appropriate experimental method, but must be confirmed by a second experiment, if resulting from a single yeast- two-hybrid experiment. For large-scale experiments interactions are referred, if a high confidence is assigned from the authors.

The format of the CC line topic INTERACTION is:

CC       {{SP_Ac:identifier[ (xeno)]}|Self}; NbExp=n; IntAct=IntAct_Protein_Ac, IntAct_Protein_Ac;


SP_Ac is the Swiss-Prot or TrEMBL accession number of the interacting protein. If appropriate, the IsoId is used instead to specify the relevant interacting protein isoform.
identifier serves to describe the interacting protein. It is derived from the Swiss-Prot or TrEMBL GN line and thus presents either a "gene name", a "ordered locus name" or a "ORF name". When no GN line is available a dash is indicated instead.
(xeno) is an optional qualifier indicating that the interacting proteins are derived from different species. This may be due to the experimental set-up or may reflect a pathogen-host interaction.
Self reflects a self-association; the corresponding current entry's SP_Ac and 'identifier' are not given/repeated.
NbExp=n refers to the number of experiments in IntAct supporting the interaction.
IntAct_Protein_Ac is the IntAct accession number of a interacting protein. The first IntAct_Protein_Ac refers to the protein or an isoform of the current entry, the second refers to the interacting protein or isoform.

Within the CC INTERACTION topic, homomeric interactions are listed before the heteromeric interactions; latter are sorted alphanumerical according the 'identifier'.

"IntAct=IntAct_Protein_Ac, IntAct_Protein_Ac" identifies the interaction in IntAct by using the two IntAct protein identifiers.

Examples of interaction lines are given below. The CC INTERACTION topics are not complete; only explained interaction lines are indicated.

CC       P11450:fcp3c; NbExp=1; IntAct=EBI-126914, EBI-159556;

In the typical example the current protein is interacting with P11450 which is further characterized by "fcp3c" derived from its GN line and presents its gene name "Fcp3C". The interaction is supported by one experiment stored in IntAct. Experimental details for this interaction can be found by quering IntAct with "EBI-126914, EBI-159556".

CC       Q9W1K5-1:cg11299; NbExp=1; IntAct=EBI-133844, EBI-212772;
CC       ...

The current protein interacts with an isoform of Q9W1K5 defined by the IsoID Q9W1K5-1.

CC       Q8NI08:-; NbExp=1; IntAct=EBI-80809, EBI-80799;

No gene name information for the interacting protein is available.

CC       Self; NbExp=1; IntAct=EBI-123485, EBI-123485;

The protein self-associates.

CC       Q8C1S0:2410018m14rik (xeno); NbExp=1; IntAct=EBI-394562, EBI-398761;

The source organisms of the interacting proteins are different.

CC       P51617:irak1; NbExp=1; IntAct=EBI-448466, EBI-358664;
CC       P51617:irak1; NbExp=1; IntAct=EBI-448472, EBI-358664;

Different isoforms of the current protein are shown to interact with the same protein (P51617). This is reflected by different IntAct_Protein_Acs for the current protein.

Example entry with many interaction lines: Q02821.

New Swiss-Prot document: similar.txt

There is a new Swiss-Prot document: similar.txt: Index of CC SIMILARITY lines. This index lists all names of families and domains occurring in CC SIMILARITY lines of Swiss-Prot entries.

Changes concerning keywords

New keywords: