Figure 5.

Cross-linking does not occur in WT, WT-Kir6.2//E203C-SUR1, or Q52C-Kir6.2//WT-SUR1 channels. (A–C) Representative traces of inside-out patch voltage-clamp recordings from COSm6 cell transfected with control WT (A), WT-Kir6.2//E203C-SUR1 (B), or Q52C-Kir6.2//WT-SUR1 (C) channels. Patches were exposed to oxidizing agent (0.2% H₂O₂, gray lines), 1 mM ATP (black lines), reducing agent (5 mM DTT, open lines), or 5 µM PIP₂ (thick dashed lines). Thin dashed lines represent zero current. Two examples of each condition are shown. Occasional decreases in current were observed with H₂O₂ exposure, but always slower and less robust than compared with Q52C-Kir6.2//E203C-SUR1 channels (Fig. 4). Furthermore, control channels remain sensitive to PIP₂ stimulation after H₂O₂ exposure, and in no case did DTT result in increased currents. Brief downward deflections seen in some of the traces are caused by solution exchange artifacts.