β1's effects on the BK_Ca channel's voltage-sensing parameters cannot account for the β1-induced changes in the ΔEΔB channel's Ca²⁺ dose–response relation. (A) ΔEΔB (open circles) and ΔEΔB + β1 (filled squares) Ca²⁺ dose–response relations normalized to their minima. (B) Simulated Ca²⁺ dose–response curves for the ΔEΔB (black curve) and ΔEΔB + β1 (gray curve) channels assuming that β1 only affects the voltage-sensing properties of the channel. The curves were simulated with an HA model using parameters we have determined previously (Bao and Cox, 2005; Sweet and Cox, 2008). For the ΔEΔB (α-only channel): L = 2e-6, Vhc =151 mV, Vho = 27 mV, E = 2.8, and zL = 0.41, and zJ = 0.58, Kc = 23.2 µM, and Ko = 4.9 µM. To simulate the effects of β1, L0 was moved to 2e-9, Vhc to 80 mV, and Vho to −34 mV. The remaining parameters were unchanged.