TY - JOUR T1 - Molecular Determinants of Potent P2X2 Antagonism Identified by Functional Analysis, Mutagenesis and Homology Docking JF - Molecular Pharmacology JO - Mol Pharmacol DO - 10.1124/mol.110.068700 SP - mol.110.068700 AU - Christian Wolf AU - Christiane Rosefort AU - Ghada Fallah AU - Matthias U. Kassack AU - Alexandra Hamacher AU - Mandy Bodnar AU - Haihong Wang AU - Peter Illes AU - Achim Kless AU - Gregor Bahrenberg AU - Gunther Schmalzing AU - Ralf Hausmann Y1 - 2010/01/01 UR - http://molpharm.aspetjournals.org/content/early/2010/12/29/mol.110.068700.abstract N2 - P2X2 receptors are members of the ATP-gated P2X family of cation channels, and they participate in neurotransmission in sympathetic ganglia and interneurons. Here, we identified NF770 as a nanomolar-potent competitive P2X2 receptor antagonist within a series of 139 suramin derivatives. Three structural determinants contributed to the inhibition of P2X2 receptors by NF770: (i) a "large urea" structure with two symmetric phenylenecarbonylimino groups; (ii) attachment of the naphthalene moiety in position 7,7'; and (iii) the specific position of two sulfonic acid groups (3, 3'; 6, 6') and of one methoxy group (1, 1') at the naphthalene moiety. This structure–activity relationship was interpreted using a rat P2X2 homology model based on the crystal structure of the closed zebrafish P2X4 receptor. Docking of the suramin derivatives into the modeled ATP-binding pocket provides a uniform explanation for the observed differences in inhibitory potencies. Changes in the chemical structure that increase the inhibitory potency of the suramin derivatives improved the spatial orientation within the ATP-binding pocket to allow for stronger polar interactions of functional groups with Gly72, Glu167 or Arg290. Gly72 is responsible for the orientation of the methoxy group close to Arg290 or Glu167. Combined mutational and functional analysis confirmed that residues Gly72 and Glu167 are as important for ATP binding as Arg290, whose ATP-binding role has been shown in previous studies. The in silico prediction of Gly72 and Glu167 as ATP-binding residues strongly supports the validity of our homology docking. ER -