The extracellualr segment of hβ2 affects the sensitivity of ChTX to mSlo1+hβ2 channels.

A–B, Traces show the representative currents obtained from outside-out patches from HEK293 cells transfected with cDNA encoding mSlo1+hβ2 and mSlo1+4K4D subunits, respectively. Currents were elicited by a 30-ms voltage step from –180 mV to 120 mV, in the presence of 10 µM Ca²⁺. The current traces are for the control, 100 nM ChTX and recovery as indicated. C. The time courses of blockade of mSlo1+hβ2 and mSlo1+4K4D by 100 nM ChTX. Each patch was perfused with 100 nM ChTX as indicated by the horizontal bars. The on-time constants of blockade by 100 nM ChTX are: τ_on = 138.3±16.9 s (n = 4) for mSlo1+hβ2 (gray circle) and τ_on = 20.0±1.3 s (n = 4) for mSlo1+4K4D (black circle).