Pituitary-specific positive transcription factor 1

POU class 1 homeobox 1, also known as pituitary-specific positive transcription factor 1 (PIT1), POU domain, class 1, transcription factor 1 (POU1F1) and growth hormone factor 1 (GHF1), is a transcription factor for growth hormone encoded by the gene POU1F1.

Function
PIT1 is part of the POU family of transcription factors. It is expressed by somatotrophic cells, as well as thyrotrophs and lactotrophs of the anterior pituitary gland. It contains a C-terminal domain for transactivation. Another domain is DNA binding—its C-terminal portion is homologous to the homeodomain consensus, common to many genes involved in development, while the other portion is POU specific, affords PIT1 specificity in its transcriptional activation of the prolactin and growth hormone genes and is involved in protein-protein interactions. Activity on thyroid stimulating hormone-beta expression is also known for PIT1.

Interactions
Pituitary-specific positive transcription factor 1 has been shown to interact with GATA2 and PITX1.