Progesterone Receptor

Progesterone receptor (PR), a transcription factor, belongs to the nuclear receptor (NR) superfamily. It is specifically regulates the expression of target genes in response to the hormonal stimulus. PR is expressed from a single gene as two isoforms, PRA and PRB. Like all nuclear receptors, PR consists of a DNA binding domain (DBD), sandwiched between an upstream N-terminal region that contains activation (AF) and inhibitory (IF) functions, and a downstream hinge region and C-terminal ligand binding domain (LBD). In the absence of progesterone, the PR is sequestered in a nonproductive form associated with heat shock proteins and other cellular chaperones. Upon progesterone binding, the PR undergoes a series of events, including conformational changes, dissociation from heat shock protein complexes, dimerization, phosphorylation, and nuclear translocation, which enables its binding to progesterone-response elements within the regulatory regions of target genes. PR is important for versatile important biological functions, especially female development, reproduction and maintenance.