Fig. 1.

Structure of fenestration aromatic residues and the ATP-induced current in HEK293 cells expressing the WT P2X₄R. a Conserved aromatic residues with large side chains in the fenestration domain (indicated by gray areas). b The models of the rP2X₄R are shown in the open or closed state, and the TM domains are shown in pink. The fenestration domain is shown in the dashed box. The model shows the position of the aromatic residues. c Example record showing the peak current activated by ATP and the effects of IVM on the peak amplitude and deactivation time of the currents induced by ATP (in this and the following figures, the traces show experimental records, and black bars indicate the duration of agonist application for 1–2 s). Concentration dependence of ATP on the peak amplitude of current responses by the WT P2X₄ receptor in the absence (n = 15, closed symbols) and presence of 3 μM IVM (n = 7, open symbols)