Figure 3. Both TMs of β1 are required for conferring the characteristic phenotype of β1-containing BK channel complexes.

(A) Cartoons depicting the chimeric constructs obtained by swapping TM protein regions between hβ1 and hβ4 subunits. Regions from β1 and β4 are given in black and grey, respectively. (B) Macroscopic current recordings obtained from I/O oocyte membrane patches expressing cbv1+β1TMs₄ (construct 4) and cbv1+β4TMs₁ (construct 5) Ca²⁺ _i = 10 µM. (C) Averaged G/G_max-V plots of constructs 1–5 obtained at Ca²⁺ _i = 10 µM. Averaged V_half (D), activation (E) and deactivation (F) time constants (τ_act, τ_deact, respectively) from constructs 1–5 obtained at 10 M Ca²⁺ _i. *Different from cbv1 (P<0.05); ^#Different from cbv1+β1 (P<0.05). Error bars correspond to SEM; each point represents the average of ≥4 patches.