<p>POU proteins are eukaryotic transcription factors containing a bipartite DNA binding domain referred to as the POU domain. The acronym POU (pronounced 'pow') is derived from the names of three mammalian transcription factors, the pituitary-specific Pit-1, the octamer-binding proteins Oct-1 and Oct-2, and the neural Unc-86 from <taxon tax_id="6239">Caenorhabditis elegans</taxon>. POU domain genes have been identified in diverse organisms including nematodes, flies, amphibians, fish and mammals 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 [<cite idref="PUB00000889"/>] and the development of an organism [<cite idref="PUB00007263"/>]. Some other genes are also regulated, including those for immunoglobulin light and heavy chains (Oct-2) [<cite idref="PUB00004699"/>, <cite idref="PUB00004053"/>], and trophic hormone genes, such as those for prolactin and growth hormone (Pit-1). </p><p>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 (<db_xref db="INTERPRO" dbkey="IPR000327"/>), while the C-terminal subunit is a homeobox domain (<db_xref db="INTERPRO" dbkey="IPR007103"/>). 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 [<cite idref="PUB00001223"/>]. The subdomains are connected by a flexible linker [<cite idref="PUB00007264"/>, <cite idref="PUB00000905"/>, <cite idref="PUB00007265"/>]. 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 [<cite idref="PUB00007264"/>, <cite idref="PUB00000905"/>].</p><p>This entry represents the POU-specific subunit of the POU domain.</p> POU-specific