Prolactin (PRL) expression in the pituitary is limited to specific cells. Pit-1 is a pituitary specific transcription factor that plays an important role in PRL expression, both in mature organism and during development. The PRL promoter contains numerous Pit-1 binding sites and these sites have been implicated in both basal level and kinase-mediated gene expression. The most proximal of these binding sites, termed 1P, has been shown to direct a response to numerous signals, such as cAMP and various G-proteins.
A novel protein, termed PREB (prolactin regulatory element binding protein), has been recently identified that regulates PRL gene expression through the 1P site, though it contains no discernable DNA-binding motif. Recent studies suggest that PREB is encoded by a single-copy gene in both mice and humans and exhibits nuclear accumulation in pituitary cells. Evidence suggests that PREB is a novel transcription factor that assists in PRL expression whether alone, or in concert with Pit-1.
Mammalian guanine nucleotide exchange factor mSec12; prolactin regulatory binding-element protein; Prolactin Regulatory Element Binding Protein; Prolactin regulatory element-binding protein