FIGURE 2.

Engineered disulfide bonds in the turret region limit P2X2 receptor function. Recordings where made in the whole-cell configuration at a holding current of −60 mV and ATP (30 μm) was applied repeatedly every 2 min for 2 s (left), or for 12 s (right). DTT (10 mm) and H₂O₂ (0.3%) were applied where indicated. P2X2(P89C/S97C) receptors had small responses to ATP which were gradually increased by DTT application in the closed channel protocol and more rapidly in the open channel protocol (A). Currents from P2X2(P90C) receptors were enhanced by DTT only in the closed channel protocol (B). The current amplitude returned slowly to baseline, and this was more rapid in the presence of H₂O₂. Application of DTT to the (P90S) control had no effect on current amplitude. There was also clear enhancement with DTT in the open channel protocol (C, right). Representative recordings of n > 4 experiments are shown.