Figure 4.

Block of synthetic HB₁₂₈/polyP channel by transition metal cation La³⁺. (A) The bilayer was formed in symmetrical bathing solutions of 200 mM CaCl₂, 5 mM MgCl₂, 10 mM Tris⋅Hepes, pH 7.4. The clamping potential was −80 mV. After incorporation of the channel, activities were recorded for 5 min. Then, La³⁺ was added to the trans compartment to achieve the indicated concentrations. The bath was stirred and activities were recorded after 1 min of addition of La³⁺. Data points represent mean values of the amplitude histograms at −80 mV clamping potential; error bars show the standard deviation from the mean. Data were filtered at 500 Hz. (B) Blockade by 100 μM La³⁺ under the experimental conditions detailed in A. Data were filtered at 1 kHz. The bars at the side of each profile indicate the fully closed state of the channel.