Figure 8.
Intracellular dialysis of 5 μm Cav3 CaMB peptides cause a hyperpolarizing shift in voltage dependence but only with Cav3.2 channels containing an intact gating brake. Scatterplot (left) with mean ± S.E. (right) values of the voltages of 50% activation (A) and steady-state inactivation (B) taken from Boltzmann fits of activation and steady-state inactivation curves for wild-type Cav3.2 channels and Cav3.2 channels with a deleted gating brake (deleted sequence from 429 to 539, see Fig. 2A). Representative current traces at time 0 min and after 20-min dialysis of Cav3.2 CaMB peptide are shown. Dialysis of CaMB peptide (after 20 min) generates a hyperpolarizing shift in voltage dependence of wild-type Cav3.2 channels, but it does not promote additional hyperpolarizing shifts in voltage dependence on the Cav3.2 channels that are highly hyperpolarizing shifted after gating brake deletion. The statistical significance after dialyses of CaMB peptide in Cav3.2 channels containing an intact gating brake is p = 0.0156 (*) and p = 0.0313 (*) for V50% activation and V50% inactivation, respectively, in a Wilcoxon matched-pairs signed rank test.