Fig. 2.

Ca²⁺-dependent CH₃SO₃⁻ currents in human bestrophin1 (hBest1) gate mutants. a Representative wild-type (WT) current traces in the presence of 1.2 μM Ca²⁺, with CH₃SO₃⁻ in the external solution. Scale bar, 200 pA, 150 ms. b–d Population steady-state current density–voltage relationships in HEK293 cells expressing hBest1 WT (b), I205A (c), or 3A (d), with CH₃SO₃⁻ in the external solution, in the absence (magenta) or presence (red) of 1.2 μM Ca²⁺, n = 5–6 for each point. *P < 0.05 compared to cells in the absence of Ca²⁺, using two-tailed unpaired Student’s t test. e Bar chart showing the steady-state CH₃SO₃⁻ current densities at 100 mV in the absence of Ca²⁺, n = 5–7 for each bar. *P < 0.05 compared to currents conducted by WT hBest1, using two-tailed unpaired Student’s t test. f Relative ion permeability ratios (P_CH3SO3/P_Cl) calculated from the Goldman–Hodgkin–Katz equation, n = 5–7 for each bar. g Relative ion conductance ratios (G_X/G_Cl) measured as slope conductance at the reversal potential plus 50 mV (CH₃SO₃⁻/Cl⁻, red) or minus 50 mV (Cl⁻/Cl⁻, black), n = 5–10 for each bar. All error bars in this figure represent s.e.m.