A possible mechanism for the anti-inducing effect of progesterone in rat liver

The mechanism of the anti-inducing effect of progesterone has been explored in the glucocorticoid receptor system from rat liver. Sodium molybdate was used to stop the reaction at the level of the binding step. On the basis of our results we propose that progesterone binds to the receptor on a site (Pro-site) which is different from the one to which binds dexamethasone (Dex-site). Moreover we suggest that progesterone induces the transition to an “incompetent form” which is able to bind dexamethasone.