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17  structures 321  species 0  interactions 1826  sequences 33  architectures

Family: Integrin_alpha (PF00357)

Summary: Integrin alpha cytoplasmic region

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

This is the Wikipedia entry entitled "Integrin". More...

Integrin Edit Wikipedia article

An integrin, or integrin receptor, is a receptor in the plasma membrane of biological cells. Integrins play an important role in:

Among the ligands of integrins are fibronectin and collagen, both part of the extracellular matrix. Ligand binding leads to clustering (cross-connection) of the multivalent components of the integrin to a functional protein complex. Integrins have no intrinsic kinase activity, but associate kinases (for example, focal adhesion kinase, FAK) on the cytoplasmic side of the membrane.

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

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.

Integrin alpha cytoplasmic region Provide feedback

This family contains the short intracellular region of integrin alpha chains.

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR018184

Some alpha subunits are cleaved post- translationally to produce a heavy and a light chain linked by a disulphide bond [ PUBMED:3028640 , PUBMED:2199285 ]. Integrin alpha chains share a conserved sequence which is found at the beginning of the cytoplasmic domain, just after the end of the transmembrane region. Within the N-terminal domain of alpha subunits, seven sequence repeats, each of approximately 60 amino acids, have been found [ PUBMED:3327687 ]. It has been predicted that these repeats assume the beta-propeller fold. The domains contain seven four-stranded beta-sheets arranged in a torus around a pseudosymmetry axis [ PUBMED:8990162 ]. Integrin ligands and a putative Mg 2+ ion are predicted to bind to the upper face of the propeller, in a manner analogous to the way in which the trimeric G-protein beta subunit (G beta) (which also has a beta-propeller fold) binds the G protein alpha subunit [ PUBMED:8990162 ].

Integrin cytoplasmic domains are normally less than 50 amino acids in length, with the beta-subunit sequences exhibiting greater homology to each other than the alpha-subunit sequences [ PUBMED:12826403 ]. This is consistent with current evidence that the beta subunit is the principal site for binding of cytoskeletal and signalling molecules, whereas the alpha subunit has a regulatory role. The first ten residues of the alpha-subunit cytoplasmic domain appear to form an alpha helix that is terminated by a proline residue. The remainder of the domain is highly acidic in nature and this loops back to contact the membrane-proximal lysine anchor residue.

This entry represents the conserved site of the C-terminal integrin alpha chain.

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.

Representative proteomes UniProt
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PP/heatmap 1 View           

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

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

Format an alignment

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.

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: Prosite
Previous IDs: integrin_A;
Type: Family
Sequence Ontology: SO:0100021
Author: Bateman A , Finn RD
Number in seed: 22
Number in full: 1826
Average length of the domain: 14.9 aa
Average identity of full alignment: 54 %
Average coverage of the sequence by the domain: 1.44 %

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 20.2 10.0
Trusted cut-off 20.2 14.8
Noise cut-off 20.1 9.9
Model length: 15
Family (HMM) version: 23
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 Integrin_alpha domain has been found. There are 17 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
A0A044UZ80 View 3D Structure Click here
A0A044V9A7 View 3D Structure Click here
A0A0G2JVZ6 View 3D Structure Click here
A0A0G2K470 View 3D Structure Click here
A0A0K0ELI9 View 3D Structure Click here
A0A0N4UF41 View 3D Structure Click here
A0A158Q537 View 3D Structure Click here
A0A183Y7I6 View 3D Structure Click here
A0A3P7FKM4 View 3D Structure Click here
A0A5S6PFE0 View 3D Structure Click here
A2ARA8 View 3D Structure Click here
A8X3A7 View 3D Structure Click here
B3DIZ6 View 3D Structure Click here
B5DEG1 View 3D Structure Click here
B8JLK8 View 3D Structure Click here
D3ZAC0 View 3D Structure Click here
D3ZWZ1 View 3D Structure Click here
E7F7L7 View 3D Structure Click here
G3V667 View 3D Structure Click here
M0R6T8 View 3D Structure Click here
P05555 View 3D Structure Click here
P06756 View 3D Structure Click here
P08514 View 3D Structure Click here
P11215 View 3D Structure Click here
P12080 View 3D Structure Click here
P20701 View 3D Structure Click here
P20702 View 3D Structure Click here
P24063 View 3D Structure Click here
P26007 View 3D Structure Click here
P26008 View 3D Structure Click here
P26009 View 3D Structure Click here
P34446 View 3D Structure Click here
P38570 View 3D Structure Click here
P43406 View 3D Structure Click here
P53708 View 3D Structure Click here
P61625 View 3D Structure Click here
P80746 View 3D Structure Click here
Q03600 View 3D Structure Click here
Q13349 View 3D Structure Click here
Q3V0T4 View 3D Structure Click here