Certain interactions between ligand and progesterone receptor have been described to be important for ligand binding (Fig. 2).
Various studies have described the presence of a hydrophobic pocket, referred as 17α pocket, which consists of Leu715, Leu718, Phe794, Leu797, Met801 and Tyr890 and appears to provide additional room for ligand expansion irrespective of agonism or antagonism.