PT - JOURNAL ARTICLE AU - Xing Liu AU - Annmarie Surprenant AU - Hong-Ju Mao AU - Sebastien Roger AU - Rong Xia AU - Helen Bradley AU - Lin-Hua Jiang TI - Identification of Key Residues Coordinating Functional Inhibition of P2X<sub>7</sub> Receptors by Zinc and Copper AID - 10.1124/mol.107.039651 DP - 2008 Jan 01 TA - Molecular Pharmacology PG - 252--259 VI - 73 IP - 1 4099 - http://molpharm.aspetjournals.org/content/73/1/252.short 4100 - http://molpharm.aspetjournals.org/content/73/1/252.full SO - Mol Pharmacol2008 Jan 01; 73 AB - P2X7 receptors are distinct from other ATP-gated P2X receptors in that they are potently inhibited by submicromolar concentrations of zinc and copper. The molecular basis for the strong functional inhibition by zinc and copper at this purinergic ionotropic receptor is controversial. We hypothesized that it involves a direct interaction of zinc and copper with residues in the ectodomain of the P2X7 receptor. Fourteen potential metal interacting residues are conserved in the ectodomain of all mammalian P2X7 receptors, none of which is homologous to previously identified sites in other P2X receptors shown to be important for functional potentiation by zinc. We introduced alanine substitutions into each of these residues, expressed wild-type and mutated receptors in human embryonic kidney 293 cells, and recorded resulting ATP and BzATP-evoked membrane currents. Agonist concentration-response curves were similar for all 12 functional mutant receptors. Alanine substitution at His62 or Asp197 strongly attenuated both zinc and copper inhibition, and the double mutant [H62A/D197A] mutant receptor was virtually insensitive to inhibition by zinc or copper. Thus, we conclude that zinc and copper inhibition is due to a direct interaction of these divalent cations with ectodomain residues of the P2X7 receptor, primarily involving combined interaction with His62 and Asp197 residues. The American Society for Pharmacology and Experimental Therapeutics