Figure 3.

Addition of an N-terminal cleavable signal sequence does not alter functional expression of MaxiK channels. Representative inside-out macropatch currents from oocytes injected with S-Hslo-M4 (A) or Hslo-M4 (B) measured in symmetrical 110 mM K⁺ in presence of 10 μM Ca²⁺. (C) Half-activation potentials (V½) as a function of intracellular [Ca²⁺]. Signal sequence fusion on a Shaker potassium channel (S-ShH4-IR) (D) and after removal of the signal sequence from the same clone (ShH4-IR(S-) (E). Currents in D and E were measured in cell attached mode. Pulses to the indicated potentials were delivered to oocytes bathed in 105 mM potassium–methane sulfonate solution.