Two model system of the alpha1A-adrenoceptor docked with selected ligands.

In this study, we have developed a two model system to mimic the active and inactive states of a G-protein coupled receptor specifically the alpha1A adrenergic receptor. We have docked two agonists, epinephrine (phenylamine type) and oxymetazoline (imidazoline type), as well as two antagonists, prazosin and 5-methylurapidil, into two alpha1A receptor models, active and inactive. The best docking complexes for both agonists had hydrophilic interactions with D106, while neither antagonist did. Prazosin and oxymetazoline had hydrophobic interactions with F308 and F312. We predict from our study that the active state is stabilized by the interaction of F193 with I114, L197, V278, F281, and V282. The active state is further stabilized by the interaction of F312 with L75, V79, and L80. We also predict that the inactive state of the receptor is stabilized by the interaction of F312 with W102, F288, and M292.