Rabbit polyclonal antibody to PR

Human progesterone receptor (PR) is expressed as two forms: the full length PR~B and the short form PR~A. PR~A lacks the first 164 amino acid residues of PR~B. Both PR~A and PR~B are ligand activated, but differ in their relative ability to activate target gene transcription. The activity of PR is regulated by phosphorylation; at least seven serine residues are phosphorylated in its amino~terminal domain. Three sites (Ser81, Ser102, and Ser162) are unique to full length PR~B, while other sites (Ser190, Ser294, Ser345, and Ser400) are shared by both isoforms. Phosphorylation of PR~B at Ser190 (equivalent to Ser26 of PR~A) is catalyzed by CDK2. Mutation of Ser190 results in decreased activity of PR, suggesting that the phosphorylation at Ser190 may be critical to its biological function.