Progesterone Receptor Antibodies

The progesterone receptor (PR) is a member of the steroid family of nuclear receptors. The PR mediates the physiological effects of progesterone, which plays a central role in reproductive events associated with the establishment and maintenance of pregnancy. PR is found as a 94 kDa protein (Form A) or a 120 kDa protein (Form B) due to the use of alternative translation initiation sites. PR-B is the transcriptionally active form and is responsible for activating genes for the maintenance of the endometrium, maintenance of pregnancy, and inhibition of ovulation. PR-A is identical to PR-B except for a 165 amino acid deletion at the N-terminus. This deletion exposes a 140 amino acid inhibitory domain (ID) that acts as a repressor of steroid hormone transcriptional activity. In its inactive state, PgR forms a multiprotein complex which includes heat shock proteins and immunophins. Upon binding of progesterone hormone to its receptor, there is a conformational change that allows dimerization and binding of the receptor to progesterone response elements (PRE) sequences, resulting in activated transcription. A Null mutation in the PGR gene leads to pleiotrophic reproductive abnormalities.