FIGURE 3.

The ability of the iNT-Cx43 peptide to inhibit Cx37 (A), Cx45 (B), Cx46 (C), and Cx50 (D) gap junctions was tested using the same V_j-dependent block protocol as in Figure 2. As a reference, the blockade of rCx40 I_j (continuous gray line) is illustrated in each panel. Unlike rCx40, none of these four connexin gap junctions were significantly inhibited by 100 μM iNT-Cx43 peptide. Actual ΔI₂ current traces from Cx45 (E) and Cx50 (F) cell pair iNT-Cx43 peptide experiments illustrating the lack of I_j current block during the +ΔV₁ (≅V_j) step, in contrast to the Cx40 experiments shown in Figure 2. Cx45 and Cx50 gap junctions are more V_j-dependent than Cx40 (half inactivation V_j = V₀ or V_½ ≅ ±30, ±40, or ±49 mV, respectively; Lin et al., 2006; Gonzalez et al., 2007). mCx45 gap junctions prominently display contingent hemichannel gating upon V_j polarity reversal, proposed by Harris et al. (1981), owing to the increased V_j-dependence and lack of fast V_j-gating kinetics of these gap junctions.