¹H-¹⁵N HSQC demonstrating that the Cx26 CT–CL complex is affected by taurine. Interactions among CT peptide, CL peptide, and taurine were further assessed by NMR. All panels display individual Cx26CL resonance peaks. In each spectra, contours are colored as follows: black, [¹⁵N]-labeled Cx26CL; red, [¹⁵N]-labeled Cx26CL plus taurine; blue, [¹⁵N]-labeled Cx26CL plus unlabeled Cx26CT; green, [¹⁵N]-labeled Cx26CL plus unlabeled Cx26CT plus taurine. Concentrations are as follows: 10 µM Cx26CL, 4 mM Cx26CT, and 30 mM taurine. (A) Resonance peaks of Cx26CL that are unaffected by taurine, by Cx26CT, or by both taurine and Cx26CT. (B) Resonance peaks of Cx26CL showing no effect of taurine (black and red overlap), an effect of the Cx26CT (blue displaced from black), and a negligible effect of taurine on the Cx26CL–Cx26CT complex (green superimposed on blue). (C) Resonance peaks demonstrating an effect of taurine on Cx26CL (displacement from red from black), an effect of Cx26CT on Cx26CL (displacement of blue from black), and, intriguingly, displacement of the Cx26CL–Cx26CT complex by taurine (green moves away from blue toward black). (D) Resonance peaks showing a site in Cx26CL that is affected differently by each of the conditions (none of the spectra overlap).