HUMAN MINERALOCORTICOID RECEPTOR INTERACTS WITH ACTIN UNDER MINERALOCORTICOID LIGAND MODULATION

The human mineralocorticoid receptor of the steroid receptor family co ntains a modular structure with domain E which is considered to be a h ormone binding domain, Recombinant protein approaches enabled us to cl early determine that this domain is also able to interact with F-actin (Kd about 2 mu M) and G-actin, Moreover, it nas revealed that this mi neralocorticoid receptor domain/actin interaction mas modulated by spe cific mineralocorticoid ligands. Agonist (aldosterone) steroid binding almost totally (91%) abolished the interaction with F-actin, while an tagonist (progesterone) binding allowed more than 30% of this binding. Steroid modulation of the interaction between domain E and actin indi cated that this actin binding is specific and could be essential for c ellular mineralocorticoid receptor activity.