Critical role of the β N terminus in determining ΔV_0.5 by PIP₂. (A) Sequence alignment of β1, β2 Δ2–19, and β2 Δ2–32 N termini. (B) Changes in G-V parameters by PIP₂ in Slo1 complexes with different β subunits. (C) Sequence alignment of β1, β2–32, and β4 N termini. (D) Changes in G-V parameters by PIP₂ in Slo1 + β1 complexes with the β1-to-β2 point mutations indicated. (E) Changes in G-V parameters by PIP₂ in Slo1 + β1 complexes with β1 mutations at position 11. (F) Changes in G-V parameters by PIP₂ in Slo1 + β2 with the β2-to-β1 point mutations indicated. (G) Changes in G-V parameters by PIP₂ in Slo1 + β4 with the β4-to-β1 (top) and β4-to-β2 (bottom) point mutations indicated. In D–F, the gray shaded areas represent the mean ± SEM of ΔV_0.5 by PIP₂ in Slo1 + β1 (left) and Slo1 + β2 Δ2-32 (right). In G, the gray shaded area shows the mean ± SEM of ΔV_0.5 by PIP₂ in Slo1 + β2 Δ2–32. All results were obtained without Ca²⁺. Error bars represent mean ± SEM.