POU domain
Encyclopedia
POU is a family of proteins that have well-conserved homeodomains.
have been described in organisms as divergent as Caenorhabditis elegans
, Drosophila
, Xenopus
, zebrafish and human but have not been yet identified in plants and fungi.
There is a surprisingly high degree of amino acid sequence conservation (37%-42%) of POU homeodomains to the transcriptional regulator comS from the gram positive prokaryote
Bacillus subtilis
. Interestingly, akin to the way that POU homeodomain regulators lead to tissue differentiation in metazoans, this transcription factor is critical for differentiation of a subpopulation of B. subtilis into a state of genetic competence.
s containing a bipartite DNA binding domain referred to as the POU domain. The acronym POU is derived from the names of three transcription factors, the pituitary-specific Pit-1
, the octamer-binding proteins Oct-1
and Oct-2
, and the neural Unc-86 from Caenorhabditis elegans
. POU domain genes have been described in organisms as divergent as Caenorhabditis elegans, Drosophila, Xenopus, zebrafish and human but have not been yet identified in plants and fungi. The various members of the POU family have a wide variety of functions, all of which are related to the function of the neuroendocrine system
and the development of an organism. Some other genes are also regulated, including those for immunoglobulin light and heavy chains (Oct-2), and trophic hormone genes, such as those for prolactin and growth hormone (Pit-1).
Etymology
The acronym POU is derived from the names of three transcription factors:- the Pituitary-specific Pit-1Pituitary-specific positive transcription factor 1POU domain, class 1, transcription factor 1 , also known as POU1F1, is a transcription factor for growth hormone.-Interactions:...
- the Octamer transcription factorOctamer transcription factorAn octamer transcription factor is a transcription factor which binds to the "ATTTGCAT" sequence.Examples include:* Oct-1 - * Oct-2 - * Oct-3/4 – * Oct-6 – * Oct-7 – * Oct-8 - * Oct-9 – * Oct-11 –...
proteins Oct-1POU2F1POU domain, class 2, transcription factor 1 is a protein that in humans is encoded by the POU2F1 gene.-Interactions:POU2F1 has been shown to interact with SNAPC4, Ku80, Glucocorticoid receptor, Sp1 transcription factor, NPAT, POU2AF1, Host cell factor C1, TATA binding protein, RELA, Nuclear...
and Oct-2Oct-2Oct-2 is a octamer transcription factor which is part of the POU family....
(octamer sequence is ATGCAAAT) - the neural Unc-86 transcription factor from Caenorhabditis elegansCaenorhabditis elegansCaenorhabditis elegans is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular and developmental biology of C. elegans was begun in 1974 by Sydney Brenner and it has since been used extensively as a model...
.
Diversity
POU domain genesGênes
Gênes is the name of a département of the First French Empire in present Italy, named after the city of Genoa. It was formed in 1805, when Napoleon Bonaparte occupied the Republic of Genoa. Its capital was Genoa, and it was divided in the arrondissements of Genoa, Bobbio, Novi Ligure, Tortona and...
have been described in organisms as divergent as Caenorhabditis elegans
Caenorhabditis elegans
Caenorhabditis elegans is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular and developmental biology of C. elegans was begun in 1974 by Sydney Brenner and it has since been used extensively as a model...
, Drosophila
Drosophila
Drosophila is a genus of small flies, belonging to the family Drosophilidae, whose members are often called "fruit flies" or more appropriately pomace flies, vinegar flies, or wine flies, a reference to the characteristic of many species to linger around overripe or rotting fruit...
, Xenopus
Xenopus
Xenopus is a genus of highly aquatic frogs native to Sub-Saharan Africa. There are 19 species in the Xenopus genus...
, zebrafish and human but have not been yet identified in plants and fungi.
There is a surprisingly high degree of amino acid sequence conservation (37%-42%) of POU homeodomains to the transcriptional regulator comS from the gram positive prokaryote
Prokaryote
The prokaryotes are a group of organisms that lack a cell nucleus , or any other membrane-bound organelles. The organisms that have a cell nucleus are called eukaryotes. Most prokaryotes are unicellular, but a few such as myxobacteria have multicellular stages in their life cycles...
Bacillus subtilis
Bacillus subtilis
Bacillus subtilis, known also as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium commonly found in soil. A member of the genus Bacillus, B. subtilis is rod-shaped, and has the ability to form a tough, protective endospore, allowing the organism to tolerate...
. Interestingly, akin to the way that POU homeodomain regulators lead to tissue differentiation in metazoans, this transcription factor is critical for differentiation of a subpopulation of B. subtilis into a state of genetic competence.
Function
POU proteins are eukaryotic transcription factorTranscription factor
In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...
s containing a bipartite DNA binding domain referred to as the POU domain. The acronym POU is derived from the names of three transcription factors, the pituitary-specific Pit-1
Pituitary-specific positive transcription factor 1
POU domain, class 1, transcription factor 1 , also known as POU1F1, is a transcription factor for growth hormone.-Interactions:...
, the octamer-binding proteins Oct-1
POU2F1
POU domain, class 2, transcription factor 1 is a protein that in humans is encoded by the POU2F1 gene.-Interactions:POU2F1 has been shown to interact with SNAPC4, Ku80, Glucocorticoid receptor, Sp1 transcription factor, NPAT, POU2AF1, Host cell factor C1, TATA binding protein, RELA, Nuclear...
and Oct-2
Oct-2
Oct-2 is a octamer transcription factor which is part of the POU family....
, and the neural Unc-86 from Caenorhabditis elegans
Caenorhabditis elegans
Caenorhabditis elegans is a free-living, transparent nematode , about 1 mm in length, which lives in temperate soil environments. Research into the molecular and developmental biology of C. elegans was begun in 1974 by Sydney Brenner and it has since been used extensively as a model...
. POU domain genes have been described in organisms as divergent as Caenorhabditis elegans, Drosophila, Xenopus, zebrafish and human but have not been yet identified in plants and fungi. The various members of the POU family have a wide variety of functions, all of which are related to the function of the neuroendocrine system
Neuroendocrinology
Neuroendocrinology is the study of the extensive interactions between the nervous system and the endocrine system, including the biological features of the cells that participate, and how they functionally communicate...
and the development of an organism. Some other genes are also regulated, including those for immunoglobulin light and heavy chains (Oct-2), and trophic hormone genes, such as those for prolactin and growth hormone (Pit-1).
Structure
The POU domain is a bipartite domain composed of two subunits separated by a non-conserved region of 15-55 aa. The N-terminal subunit is known as the POU-specific (POUs) domain , while the C-terminal subunit is a homeobox domain . 3D structures of complexes including both POU subdomains bound to DNA are available. Both subdomains contain the structural motif 'helix-turn-helix', which directly associates with the two components of bipartite DNA binding sites, and both are required for high affinity sequence-specific DNA-binding. The domain may also be involved in protein-protein interactions. The subdomains are connected by a flexible linker. In proteins a POU-specific domain is always accompanied by a homeodomain. Despite of the lack of sequence homology, 3D structure of POUs is similar to 3D structure of bacteriophage lambda repressor and other members of HTH_3 family.Examples
Human genes encoding proteins containing the Pou domain include:- POU1F1Pituitary-specific positive transcription factor 1POU domain, class 1, transcription factor 1 , also known as POU1F1, is a transcription factor for growth hormone.-Interactions:...
; - POU2F1POU2F1POU domain, class 2, transcription factor 1 is a protein that in humans is encoded by the POU2F1 gene.-Interactions:POU2F1 has been shown to interact with SNAPC4, Ku80, Glucocorticoid receptor, Sp1 transcription factor, NPAT, POU2AF1, Host cell factor C1, TATA binding protein, RELA, Nuclear...
; POU2F2Oct-2Oct-2 is a octamer transcription factor which is part of the POU family....
; POU2F3POU2F3POU domain, class 2, transcription factor 3 is a protein that in humans is encoded by the POU2F3 gene.-Further reading:...
; - POU3F1POU3F1POU domain, class 3, transcription factor 1 is a protein that in humans is encoded by the POU3F1 gene....
; POU3F2POU3F2POU domain, class 3, transcription factor 2 is a protein that in humans is encoded by the POU3F2 gene....
; POU3F3; POU3F4POU3F4POU domain, class 3, transcription factor 4 is a protein that in humans is encoded by the POU3F4 gene. Mutations in POU3F4, located on the X chromosome, may cause deafness. The role of POU3F4 in the hypothalamus where it was originally described remains unknown....
; - POU4F1POU4F1POU domain, class 4, transcription factor 1 also known as brain-specific homeobox/POU domain protein 3A , homeobox/POU domain protein RDC-1 or Oct-T1 is a protein that in humans is encoded by the POU4F1 gene....
; POU4F2POU4F2POU domain, class 4, transcription factor 2 is a protein that in humans is encoded by the POU4F2 gene.-Interactions:POU4F2 has been shown to interact with Estrogen receptor alpha....
; POU4F3POU4F3POU domain, class 4, transcription factor 3 is a protein that in humans is encoded by the POU4F3 gene....
; - POU5F1; POU5F1P1; POU5F1P3; POU5F1P4; POU5F2;
- POU6F2