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51  structures 8350  species 0  interactions 18206  sequences 122  architectures

Family: Peptidase_S24 (PF00717)

Summary: Peptidase S24-like

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Peptidase S24-like Provide feedback

No Pfam abstract.

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR015927

This entry represents a stuctural domain superfamily found in serine peptidases belonging to MEROPS peptidase families: S24 (LexA family, clan SF); S26A (signal peptidase I), S26B (signalase) and S26C TraF peptidase. This domain has a complex fold made of several coiled beta-sheets, which contains an SH3-like barrel structure.

The S26 family includes Escherichia coli signal peptidase, SPase, which is a membrane-bound endopeptidase with two N-terminal transmembrane segments and a C-terminal catalytic region [ PUBMED:9823901 ]. SPase functions to release proteins that have been translocated into the inner membrane from the cell interior, by cleaving off their signal peptides. In SPase proteins, this domain is disrupted by the insertion of an additional all-beta subdomain.

  • Note: This signature covers both the SH3-like barrel beta-ribbon domain and the all-beta subdomain inserted into it.

The S24 family includes:

  • the lambda repressor CI/C2 family and related bacterial prophage repressor proteins [ PUBMED:10892750 ].
  • LexA, the repressor of genes in the cellular SOS response to DNA damage [ PUBMED:11551506 ].
  • MucA and the related UmuD proteins, which are lesion-bypass DNA polymerases, induced in response to mitogenic DNA damage [ PUBMED:8994967 ]. UmuD is self-processed by its own serine protease activity during the SOS response.
  • RulA, a component of the rulAB locus that confers resistance to UV.

All of these proteins, with the possible exception of RulA, interact with RecA, which activates self cleavage either derepressing transcription in the case of CI and LexA [ PUBMED:10692372 ] or activating the lesion-bypass polymerase in the case of UmuD and MucA. UmuD'2, is the homodimeric component of DNA pol V, which is produced from UmuD by RecA-facilitated self-cleavage. The first 24 N-terminal residues of UmuD are removed; UmuD'2 is a DNA lesion bypass polymerase [ PUBMED:10692372 , PUBMED:11483531 ]. MucA [ PUBMED:9925794 , PUBMED:11016960 ], like UmuD, is a plasmid encoded a DNA polymerase (pol RI) which is converted into the active lesion-bypass polymerase by a self-cleavage reaction involving RecA [ PUBMED:11114935 ].

This group of proteins also contains proteins not recognised as peptidases as well as those classified as non-peptidase homologues as they either have been found experimentally to be without peptidase activity, or lack amino acid residues that are believed to be essential for catalytic activity.

Domain organisation

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

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Pfam Clan

This family is a member of clan Peptidase_SF (CL0299), which has the following description:

This clan includes the peptidase S24 and S26 families. These families adopt a mainly beta fold. Members of the family S24 have an additional C-terminal domain containing a bundle of three helices presumably important for binding DNA.

The clan contains the following 3 members:

Peptidase_S24 Peptidase_S26 Phage_CI_C


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.

Representative proteomes UniProt
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Representative proteomes UniProt

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We make all of our alignments available in Stockholm format. You can download them here as raw, plain text files or as gzip-compressed files.

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

HMM logo

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: Pfam-B_616 (release 2.1)
Previous IDs: none
Type: Domain
Sequence Ontology: SO:0000417
Author: Bateman A , Finn RD
Number in seed: 95
Number in full: 18206
Average length of the domain: 115.9 aa
Average identity of full alignment: 23 %
Average coverage of the sequence by the domain: 53.16 %

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 23.3 23.3
Trusted cut-off 23.3 23.3
Noise cut-off 23.2 23.2
Model length: 116
Family (HMM) version: 26
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 Peptidase_S24 domain has been found. There are 51 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
A0A044QWB3 View 3D Structure Click here
A0A077ZFD1 View 3D Structure Click here
A0A077ZK55 View 3D Structure Click here
A0A0D2F1V0 View 3D Structure Click here
A0A0H3GN19 View 3D Structure Click here
A0A0H3GP86 View 3D Structure Click here
A0A0H3GQ57 View 3D Structure Click here
A0A0H3H1L6 View 3D Structure Click here
A0A0J9Y5K5 View 3D Structure Click here
A0A0K0EEP2 View 3D Structure Click here
A0A0N4U782 View 3D Structure Click here
A0A0R0JK02 View 3D Structure Click here
A0A1C1CFT4 View 3D Structure Click here
A0A1D6QAA1 View 3D Structure Click here
A0A3P7EEP0 View 3D Structure Click here
A0JUZ2 View 3D Structure Click here
A0L9E2 View 3D Structure Click here
A0LGS1 View 3D Structure Click here
A0LUZ1 View 3D Structure Click here
A0Q0N2 View 3D Structure Click here
A0QVY5 View 3D Structure Click here
A1A2G3 View 3D Structure Click here
A1B3Z0 View 3D Structure Click here
A1CL29 View 3D Structure Click here
A1D6D8 View 3D Structure Click here
A1K776 View 3D Structure Click here
A1R556 View 3D Structure Click here
A1SBC7 View 3D Structure Click here
A1SND2 View 3D Structure Click here
A1SR67 View 3D Structure Click here
A1T7V4 View 3D Structure Click here
A1TQ93 View 3D Structure Click here
A1UF04 View 3D Structure Click here
A1VNK0 View 3D Structure Click here
A1W897 View 3D Structure Click here
A1WSJ3 View 3D Structure Click here
A1WXU3 View 3D Structure Click here
A2SGY5 View 3D Structure Click here
A3DDH9 View 3D Structure Click here
A3LXS1 View 3D Structure Click here