Figure 7. Position C271, but not C260 and C298, was S-nitrosylated and mediated NO-induced hemichannel currents.

(A) Representative current traces for oocytes expressing Cx43 with a deleted CT and Cx43 mutants C260S, C271S, and C298S. Black and red traces correspond to voltage step–evoked currents in the absence or presence of 10 μM DEENO, respectively. Oocytes were clamped to −80 mV, and square pulses from −80 mV to +90 mV (in 10-mV steps) were then applied for 2 seconds. At the end of each pulse, the membrane potential was returned to −80 mV. Graph shows normalized fold increase of DEENO current after treatment at different voltages. The number in parentheses indicates the n value. Comparisons between groups were made using 2-way ANOVA plus Tukey’s post hoc test; *P < 0.05 vs. Cx43ΔCT; ^†P < 0.05 vs. Cx43C271. (B) DEENO decreased the resting membrane potential in oocytes expressing Cx43 mutants C260S and C298S but not in those expressing the Cx43ΔCT or Cx43 mutant C271S. The number in parentheses indicates the n value. Comparisons between groups were made using 2-way ANOVA test; *P < 0.05 vs. control. (C) Top gel was loaded with S-nitrosylated proteins pulled down using the biotin switch assay and blotted against Cx43. Bottom Western blot was loaded with total proteins of oocytes expressing Cx43 against Cx43. The number in parentheses indicates the n value. Comparisons between groups were made using Student’s t test; *P < 0.05 vs. control.