Effects of subunit liganding on activation kinetics. (A) Superimposition of activation time courses in the presence and in the absence of cAMP at −140 mV for wwww and illustration of determining the activation time constant τa (monoexponential fits are shown in red). Late currents are normalized. (B) Voltage dependence of τa and effect of cAMP for wwww (n = 13–17 recordings per data point). Green and black symbols show values obtained at 50 µM and zero cAMP, respectively. (C) Comparison of τa for the eight tetrameric concatemers and the dimeric concatemer wm2 at hyperpolarization to −140 mV. Data points contain 9–17 recordings. (D) τa values in dependence on normalized voltage. Shown are individual data points. Green and black symbols show values obtained at 50 µM and zero cAMP, respectively. Normalization was performed by the respective Vh value of the individual recordings. Error bars indicate SEM.
