Fig. 3: Alb reversibly activates hHv1, shifting activation to more negative voltages.
a Proton current for hHv1 channels expressed in HEK293T cells before (left), and in the presence of 75 µM Alb (right), with steps of 20 mV from −60 mV to +40 mV. The current measured at the end of depolarization was used to determine the extent of activation. Fitting the activation and deactivation of proton currents at 0 mV to a single exponential function gave time constants τact of 2619.8 ± 222.3 ms and 332.3 ± 30.6 ms, τtail of 86.9 ± 8.4 ms and 235.0 ± 29.7 ms without and with Alb, respectively. b G-V for hHv1 in the absence (black squares) or presence of 75 µM Alb (black circles). hHv1 channels showed a −23 ± 3 mV shift after exposure to 75 µM Alb from 15 ± 2 mV to −8 ± 1 mV. Curves fit to a Boltzmann equation, n = 6 cells. c Time course for activation and deactivation of hHv1 currents on acute application (bar) and washout of 75 µM Alb. Currents were recorded at 0 mV. Values are normalized to the control current before the application of Alb. d Dose-response relationships for Alb activation of hHv1 at 0 mV. The EC50 was estimated from a fit to the Hill relationship to be 74.8 ± 8.7 µM with a coefficient of 1.16 ± 0.11. Values are normalized to mean proton currents amplitude in the absence of Alb, n = 6–8 cells. e Cartoon showing two C6 peptides binding to an intact dimeric hHv1 channel. f C6 peptide (20 μM, red trace) was applied to cells after control pulses (black trace) without Alb (left) or after pre-activation with 75 μM Alb (right). C6 inhibited ~92% of hHv1 proton current (left), which is similar to the extent of inhibition (~89%) with Alb pre-activation (right). Values are mean ± SEM. Some error bars are smaller than symbols. Source data are provided in the Source Data file.
