Fig. 5.

Concentration dependency of PI(4)P on channel activity. A, Representative recordings of single-channel activity evoked by the concentration of PI(4)P in the absence (left) and presence (right) of 30 mm Na⁺. Traces were recorded at least 1 min after the change in PI(4)P concentration. B, Plot of the open probability (ordinate) as a function of the concentration of PI(4)P (abscissa) in the absence (filled diamonds) and presence (open circles) of 30 mm Na⁺.Inset, Same plot on an expanded ordinate. Points obtained from 1 min recordings (n = 4).Solid lines through the data points in Brepresent fits by Hill equations with the following parameters: EC₅₀, 3.2 ± 0.4 μm for 0 mm Na⁺ and 1.3 ± 0.3 μm for 30 mm Na⁺;y₀, 0.0003 ± 0.0007 for 0 mmNa⁺ and 0.05 ± 0.04 for 30 mmNa⁺; y₁, 0.0109 ± 0.0012 for 0 mm Na⁺ and 0.56 ± 0.07 for 30 mm Na⁺; andk, 2.8 ± 0.8 for 0 mmNa⁺ and 1.7 ± 0.7 for 30 mmNa⁺. The parameters are given as mean ± SE.