Invitrogen™ p23 Polyclonal Antibody

Steroid receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate hormone. Prior to activation, steroid receptors associate with a number of different proteins in both a stable and transient fashion. Steroid receptor complex proteins include heat shock proteins (HSP70 and HSP90), immunosuppressant binding proteins called immunophilins (the FK506 binding proteins, FKBP52 & FKBP54 and the cyclosporin binding protein, CyP-40) and at least three other proteins termed p23, p60 and p48. p23 along with HSP70, HSP90 and p60, combine with progesterone receptor (PR) as members of a transient intermediate complex. Cloned human p23 encodes a protein of 160 amino acids that is highly conserved between species and shows no homology to previously identified proteins. p23 is a highly acidic phosphoprotein with an aspartic acid-rich C-terminal domain and multiple potential phosphorylation sites. In vitro studies have suggested that p23 binds to HSP90 and is necessary for the binding of HSP90 and CyP-40 to PR. While neither its exact function nor mechanism of action have been identified, p23 appears to be an important factor in PR function.