Figure 2.

Ability of 10 mM Mg²⁺ to promote channel gating is decreased in the presence of β4. (A) BK α (top) and α+β4 (bottom) currents are recorded in 60 μM Ca²⁺/0 Mg²⁺ (left) and 60 μM Ca²⁺/10 mM Mg²⁺ (right). (B) Conductance–voltage relationships in 60 μM Ca²⁺ with (5 patches for α and 9 patches α+β4) and without 10 mM MgCl₂ (9 patches for α and 17 patches α+β4) or (C) nominally 0 Ca²⁺ with (7 patches for α and 6 patches α+β4) and without (12 patches for α and 6 patches α+β4) 10 mM MgCl₂. Error bars represent SEM.