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36  structures 2255  species 0  interactions 3809  sequences 11  architectures

Family: GPW_gp25 (PF04965)

Summary: Baseplate wedge protein gp25

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Baseplate wedge protein gp25 Provide feedback

This family represents T4 phage gp25 protein and gp25-like proteins, found in several systems, including contractile tail bacteriophages, the type VI secretion system (T6SS) and R-type pyocins, which constitute a multiprotein tubular apparatus to attach to and penetrate host cell membranes. Gp25 is a component of the conserved wedge in the inner part of the baseplate and serves as a nucleus for sheath polymerisation, playing a critical role in sheath assembly and contraction [1,2]. The EPR motif (Glu-Pro-Arg, residues 85-87 of gp25) is conserved across all members of the family including orthologs from the RpoS-mediated general stress response system (called IraD) [3]. This motif interacts with the 'core bundle' composed of orthologs of T4 gp6 and gp7 proteins in contractile injection systems.

Literature references

  1. Taylor NM, Prokhorov NS, Guerrero-Ferreira RC, Shneider MM, Browning C, Goldie KN, Stahlberg H, Leiman PG;, Nature. 2016;533:346-352.: Structure of the T4 baseplate and its function in triggering sheath contraction. PUBMED:27193680 EPMC:27193680

  2. Lossi NS, Dajani R, Freemont P, Filloux A;, Microbiology. 2011;157:3292-3305.: Structure-function analysis of HsiF, a gp25-like component of the type VI secretion system, in Pseudomonas aeruginosa. PUBMED:21873404 EPMC:21873404

  3. Battesti A, Majdalani N, Gottesman S;, Annu Rev Microbiol. 2011;65:189-213.: The RpoS-mediated general stress response in Escherichia coli. PUBMED:21639793 EPMC:21639793

Internal database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR007048

This domain is found in baseplate protein Gp25 from phage T4 and related phages, and Gp25-like proteins from bacteria [ PUBMED:3520236 , PUBMED:21873404 ]. It is also found in IraD, from E. coli, an 'antiadapter' protein that prevents RssB adapter-mediated degradation of RpoS by the ClpXP protease [ PUBMED:21639793 ].

Domain organisation

Below is a listing of the unique domain organisations or architectures in which this domain is found. More...

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We store a range of different sequence alignments for families. As well as the seed alignment from which the family is built, we provide the full alignment, generated by searching the sequence database (reference proteomes) using the family HMM. We also generate alignments using four representative proteomes (RP) sets and the UniProtKB sequence database. More...

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We make a range of alignments for each Pfam-A family. You can see a description of each above. You can view these alignments in various ways but please note that some types of alignment are never generated while others may not be available for all families, most commonly because the alignments are too large to handle.

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Representative proteomes UniProt

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You can also download a FASTA format file containing the full-length sequences for all sequences in the full alignment.

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HMM logos is one way of visualising profile HMMs. Logos provide a quick overview of the properties of an HMM in a graphical form. You can see a more detailed description of HMM logos and find out how you can interpret them here. More...


This page displays the phylogenetic tree for this family's seed alignment. We use FastTree to calculate neighbour join trees with a local bootstrap based on 100 resamples (shown next to the tree nodes). FastTree calculates approximately-maximum-likelihood phylogenetic trees from our seed alignment.

Note: You can also download the data file for the tree.

Curation and family details

This section shows the detailed information about the Pfam family. You can see the definitions of many of the terms in this section in the glossary and a fuller explanation of the scoring system that we use in the scores section of the help pages.

Curation View help on the curation process

Seed source: COG3628
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Bateman A , Chuguransky S
Number in seed: 208
Number in full: 3809
Average length of the domain: 95.40 aa
Average identity of full alignment: 21 %
Average coverage of the sequence by the domain: 66.00 %

HMM information View help on HMM parameters

HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 27.2 27.2
Trusted cut-off 27.2 27.2
Noise cut-off 27.1 27.1
Model length: 95
Family (HMM) version: 17
Download: download the raw HMM for this family

Species distribution

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Colour assignments

Archea Archea Eukaryota Eukaryota
Bacteria Bacteria Other sequences Other sequences
Viruses Viruses Unclassified Unclassified
Viroids Viroids Unclassified sequence Unclassified sequence


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This visualisation provides a simple graphical representation of the distribution of this family across species. You can find the original interactive tree in the adjacent tab. More...

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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the GPW_gp25 domain has been found. There are 36 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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AlphaFold Structure Predictions

The list of proteins below match this family and have AlphaFold predicted structures. Click on the protein accession to view the predicted structure.

Protein Predicted structure External Information
A9MQN1 View 3D Structure Click here
P39375 View 3D Structure Click here
Q83P77 View 3D Structure Click here
Q8XBA4 View 3D Structure Click here
Q8ZM27 View 3D Structure Click here
Q9I745 View 3D Structure Click here