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34  structures 432  species 0  interactions 3916  sequences 66  architectures

Family: STAT_alpha (PF01017)

Summary: STAT protein, all-alpha domain

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This is the Wikipedia entry entitled "STAT protein". More...

STAT protein Edit Wikipedia article

Domains and covalent modification sites of STAT proteins.
STAT protein, all-alpha domain
STAT protein, DNA binding domain
STAT protein, protein interaction domain
Dictyostelium STAT, coiled coil
PDB 1uur EBI.jpg
structure of an activated dictyostelium stat in its DNA-unbound form

Members of the signal transducer and activator of transcription (STAT) protein family are intracellular transcription factors that mediate many aspects of cellular immunity, proliferation, apoptosis and differentiation. They are primarily activated by membrane receptor-associated Janus kinases (JAK). Dysregulation of this pathway is frequently observed in primary tumors and leads to increased angiogenesis which enhances the survival of tumors and immunosuppression. Gene knockout studies have provided evidence that STAT proteins are involved in the development and function of the immune system and play a role in maintaining immune tolerance and tumor surveillance.

STAT family

The first two STAT proteins were identified in the interferon system. There are seven mammalian STAT family members that have been identified: STAT1, STAT2, STAT3, STAT4, STAT5 (STAT5A and STAT5B), and STAT6. STAT1 homodimers are involved in type II interferon signalling, and bind to the GAS (Interferon-Gamma Activated Sequence) promoter to induce expression of ISG (Interferon Stimulated Genes). In type I interferon signaling, STAT1-STAT2 heterodimer combines with IRF9 (Interferon Response Factor) to form ISGF3 (Interferon Stimulated Gene Factor), which binds to the ISRE (Interferon-Stimulated Response Element) promoter to induce ISG expression.


All seven STAT proteins share a common structural motif consisting of an N-terminal domain followed by a coiled-coil, DNA-binding, linker, Src homology 2 (SH2), and a C-terminal transactivation domain. Much research has focused on elucidating the roles each of these domains play in regulating different STAT isoforms. Both the N-terminal and SH2 domains mediate homo or heterodimer formation, while the coiled-coil domain functions partially as a nuclear localization signal (NLS). Transcriptional activity and DNA association are determined by the transactivation and DNA-binding domains, respectively.


Extracellular binding of cytokines or growth factors induce activation of receptor-associated Janus kinases, which phosphorylate a specific tyrosine residue within the STAT protein promoting dimerization via their SH2 domains. The phosphorylated dimer is then actively transported to the nucleus via an importin α/β ternary complex. Originally, STAT proteins were described as latent cytoplasmic transcription factors as phosphorylation was thought to be required for nuclear retention. However, unphosphorylated STAT proteins also shuttle between the cytosol and nucleus, and play a role in gene expression. Once STAT reaches the nucleus, it binds to a consensus DNA-recognition motif called gamma-activated sites (GAS) in the promoter region of cytokine-inducible genes and activates transcription. The STAT protein can be dephosphorylated by nuclear phosphatases, which leads to inactivation of STAT and subsequent transport out of the nucleus by a exportin-RanGTP complex.

See also

Additional images


  1. ^ Vinkemeier U, Moarefi I, Darnell JE, Kuriyan J (February 1998). "Structure of the amino-terminal protein interaction domain of STAT-4". Science. 279 (5353): 1048–52. doi:10.1126/science.279.5353.1048. PMID 9461439.

External links

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.

STAT protein, all-alpha domain Provide feedback

STAT proteins (Signal Transducers and Activators of Transcription) are a family of transcription factors that are specifically activated to regulate gene transcription when cells encounter cytokines and growth factors. STAT proteins also include an SH2 domain PF00017.

Literature references

  1. Becker S, Groner B, Muller CW; , Nature 1998;394:145-151.: Three-dimensional structure of the Stat3beta homodimer bound to DNA. PUBMED:9671298 EPMC:9671298

  2. Vinkemeier U, Moarefi I, Darnell JE Jr, Kuriyan J; , Science 1998;279:1048-1052.: Structure of the amino-terminal protein interaction domain of STAT-4. PUBMED:9461439 EPMC:9461439

Internal database links

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR013800

The STAT protein (Signal Transducers and Activators of Transcription) family contains transcription factors that are specifically activated to regulate gene transcription when cells encounter cytokines and growth factors, hence they act as signal transducers in the cytoplasm and transcription activators in the nucleus [ PUBMED:12039028 ]. Binding of these factors to cell-surface receptors leads to receptor autophosphorylation at a tyrosine, the phosphotyrosine being recognised by the STAT SH2 domain, which mediates the recruitment of STAT proteins from the cytosol and their association with the activated receptor. The STAT proteins are then activated by phosphorylation via members of the JAK family of protein kinases, causing them to dimerise and translocated to the nucleus, where they bind to specific promoter sequences in target genes. In mammals, STATs comprise a family of seven structurally and functionally related proteins: Stat1, Stat2, Stat3, Stat4, Stat5a and Stat5b, Stat6. STAT proteins play a critical role in regulating innate and acquired host immune responses. Dysregulation of at least two STAT signalling cascades (i.e. Stat3 and Stat5) is associated with cellular transformation.

Signalling through the JAK/STAT pathway is initiated when a cytokine binds to its corresponding receptor. This leads to conformational changes in the cytoplasmic portion of the receptor, initiating activation of receptor associated members of the JAK family of kinases. The JAKs, in turn, mediate phosphorylation at the specific receptor tyrosine residues, which then serve as docking sites for STATs and other signalling molecules. Once recruited to the receptor, STATs also become phosphorylated by JAKs, on a single tyrosine residue. Activated STATs dissociate from the receptor, dimerise, translocate to the nucleus and bind to members of the GAS (gamma activated site) family of enhancers.

The seven STAT proteins identified in mammals range in size from 750 and 850 amino acids. The chromosomal distribution of these STATs, as well as the identification of STATs in more primitive eukaryotes, suggest that this family arose from a single primordial gene. STATs share 6 structurally and functionally conserved domains including: an N-terminal domain (ND) that strengthens interactions between STAT dimers on adjacent DNA-binding sites; a coiled-coil STAT domain (CCD) that is implicated in protein-protein interactions; a DNA-binding domain (DBD) with an immunoglobulin-like fold similar to p53 tumour suppressor protein; an EF-hand-like linker domain connecting the DNA-binding and SH2 domains; an SH2 domain ( INTERPRO ) that acts as a phosphorylation-dependent switch to control receptor recognition and DNA-binding; and a C-terminal transactivation domain [ PUBMED:9630226 , PUBMED:18433722 , PUBMED:15780933 ]. The crystal structure of the N terminus of Stat4 reveals a dimer. The interface of this dimer is formed by a ring-shaped element consisting of five short helices. Several studies suggest that this N-terminal dimerisation promotes cooperativity of binding to tandem GAS elements and with the transcriptional coactivator CBP/p300.

This entry represents the all-alpha helical domain, which consists of four long helices arranged in a bundle with a left-handed twist (coiled-coil), which in turn forms a right-handed superhelix.

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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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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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.

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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_856 (release 3.0)
Previous IDs: STAT;
Type: Family
Sequence Ontology: SO:0100021
Author: Bateman A , Griffiths-Jones SR
Number in seed: 55
Number in full: 3916
Average length of the domain: 163.60 aa
Average identity of full alignment: 33 %
Average coverage of the sequence by the domain: 22.51 %

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 27.5 27.5
Trusted cut-off 27.5 27.5
Noise cut-off 27.4 27.4
Model length: 169
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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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 STAT_alpha domain has been found. There are 34 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
A0A0G2JX93 View 3D Structure Click here
A0A286Y960 View 3D Structure Click here
A0A2R8Q947 View 3D Structure Click here
B0S789 View 3D Structure Click here
E7FBV9 View 3D Structure Click here
F1QWX2 View 3D Structure Click here
O02799 View 3D Structure Click here
O93599 View 3D Structure Click here
P40763 View 3D Structure Click here
P42224 View 3D Structure Click here
P42225 View 3D Structure Click here
P42226 View 3D Structure Click here
P42227 View 3D Structure Click here
P42228 View 3D Structure Click here
P42229 View 3D Structure Click here
P42230 View 3D Structure Click here
P42231 View 3D Structure Click here
P42232 View 3D Structure Click here
P51692 View 3D Structure Click here
P52630 View 3D Structure Click here
P52631 View 3D Structure Click here
P52632 View 3D Structure Click here
P52633 View 3D Structure Click here
P61635 View 3D Structure Click here
Q14765 View 3D Structure Click here
Q19S50 View 3D Structure Click here
Q1KQ07 View 3D Structure Click here
Q24151 View 3D Structure Click here
Q5XI26 View 3D Structure Click here
Q61AP6 View 3D Structure Click here
Q62771 View 3D Structure Click here
Q68SP3 View 3D Structure Click here
Q6DV79 View 3D Structure Click here
Q6P943 View 3D Structure Click here
Q764M5 View 3D Structure Click here
Q7QDU4 View 3D Structure Click here
Q95115 View 3D Structure Click here
Q9NAD6 View 3D Structure Click here
Q9TUM3 View 3D Structure Click here
Q9TUZ0 View 3D Structure Click here