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30  structures 1412  species 0  interactions 2184  sequences 16  architectures

Family: LTXXQ (PF07813)

Summary: LTXXQ motif family protein

Pfam includes annotations and additional family information from a range of different sources. These sources can be accessed via the tabs below.

The Pfam group coordinates the annotation of Pfam families in Wikipedia, but we have not yet assigned a Wikipedia article to this family. If you think that a particular Wikipedia article provides good annotation, please let us know.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

LTXXQ motif family protein Provide feedback

This protein family includes two copies of a five residue motif is found in a number of bacterial proteins bearing similarity to the protein CpxP (P32158). This is a periplasmic protein that aids in combating extracytoplasmic protein-mediated toxicity, and may also be involved in the response to alkaline pH [1]. Another member of this family, Spy (P77754) is also a periplasmic protein that may be involved in the response to stress [2]. The homology between CpxP and Spy may indicate that these two proteins are functionally related [1].

Literature references

  1. Danese PN, Silhavy TJ; , J Bacteriol 1998;180:831-839.: CpxP, a stress-combative member of the Cpx regulon. PUBMED:9473036 EPMC:9473036

  2. Hagenmaier S, Stierhof YD, Henning U; , J Bacteriol 1997;179:2073-2076.: A new periplasmic protein of Escherichia coli which is synthesized in spheroplasts but not in intact cells. PUBMED:9068658 EPMC:9068658

  3. Kwon E, Kim DY, Gross CA, Gross JD, Kim KK;, Protein Sci. 2010; [Epub ahead of print]: The crystal structure Escherichia coli Spy. PUBMED:20799348 EPMC:20799348

Internal database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR012899

This family summarizes bacterial proteins related to CpxP, a periplasmic protein that forms part of a two-component system which acts as a global modulator of cell-envelope stress in Gram-negative bacteria. CpxP aids in combating extracytoplasmic protein-mediated toxicity, and may also be involved in the response to alkaline pH [ PUBMED:9473036 ]. Functioning as a dimer, it inhibits activation of the kinase CpxA, but also plays a vital role in the quality control system of P pili. It has been suggested that CpxP directly interacts with CpxA via its concave polar surface [ PUBMED:21239493 ]. Another member of this family, Spy, is also a periplasmic protein that may be involved in the response to stress [ PUBMED:9068658 ]. The homology between CpxP and Spy suggests similar functions. A characteristic 5-residue sequence motif LTXXQ is found repeated twice in many members of this family [ PUBMED:20799348 ].

Gene Ontology

The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.

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 LTXXQ-like (CL0515), which has the following description:

This is a superfamily of members all carrying the repeated LTxxQ paired sequence-motif region.

The clan contains the following 4 members:

DUF3826 DUF4890 LTXXQ Metal_resist


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...

View options

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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1Cannot generate PP/Heatmap alignments for seeds; no PP data available

Key: ✓ available, x not generated, not available.

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Representative proteomes UniProt

Download options

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.

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.

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_6101 (release 14.0)
Previous IDs: none
Type: Family
Sequence Ontology: SO:0100021
Author: Bateman A , Fenech M
Number in seed: 37
Number in full: 2184
Average length of the domain: 98.1 aa
Average identity of full alignment: 17 %
Average coverage of the sequence by the domain: 54.71 %

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 24.3 24.3
Trusted cut-off 24.3 24.3
Noise cut-off 24.2 24.2
Model length: 98
Family (HMM) version: 15
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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The tree shows the occurrence of this domain across different species. 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 LTXXQ domain has been found. There are 30 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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