β3a-mediated slow tail time constants do not change as number of β3a subunits in a BK channel complex is reduced. (A) Currents are from 4 different patches each obtained from the indicated nominal injection ratios of β3a:α message. For each patch, trypsin was later applied to remove inactivation, and the slow tail amplitude was normalized to the outward BK current at +160 mV. The increase in non-inactivating current as the mole fraction of β3a is reduced reflects the decrease in the average number of β3a subunits per BK channel. The inset shows normalized slow tails for this set of patches, indicative that the slow tail current is not appreciably changing. (B) Mean (+SD) time constants for the given injection ratios reveal no major change with β3a stoichiometry, although the normalized slow tail amplitude (red symbols) is markedly reduced. (C) Example traces are from a single β3a+α patch exposed to trypsin for the indicated cumulative durations. The inset shows normalized slow tail currents at 0, 10, and 20 s of trypsin digestion. (D) Individual slow tail time constants from 5 patches at different times of trypsin digestion are plotted as a function of measured f_ss, for the same set of patches. Each individual patch is plotted with a given color for both the time constant and the amplitude.