The POU1F1 gene is mapped to chromosome 3p11.2, where it encodes a 33 kDa pituitary-specific transcription factor present in somatotrophs, lactotrophs and thyrotrophs of the mature pituitary. The embryonal expression of POU1F1 precedes that of GH and (TSH)b. POU1F1 is responsible for pituitary development and hormone expression by activating growth hormone and prolactin genes. Specifically, it binds to the consensus sequence 5'-TAAAT-3' of these genes.
Defects in this protein are the cause of combined pituitary hormone deficiency 1, a condition characterized by pleiotropic deficiencies of growth hormone, prolactin and thyroid-stimulating hormone, while the production of adrenocorticotropic hormone, luteinizing hormone, and follicle-stimulating hormone are preserved.