Progestin binding in benign hyperplastic prostatic tissue.

The identification of saturable binding sites for promegestone (17 alpha, 21-dimethyl-19-norpregna-4,9-diene-3,20-dione) in human prostatic cytosol as progesterone receptors is complicated by some differences in binding behaviour between progesterone and promegestone. These differences seem to result from the presence in cytosol of a second class of progestin-binding sites, which has a higher affinity for progesterone than for promegestone.