FIGURE 3.

Inhibition of EP formation by binding of BeF_x and AlF_x to E1Ca₂. The E1Ca₂ state ATPase of SR vesicles in 0.1 or 5 mm free Ca²⁺ was treated for 30 min at 25 °C with fluoride compounds in the presence of the indicated concentrations of the ligands. Subsequently, the samples were cooled to 0 °C and phosphorylated for 3 s by 3 μm [γ-³²P]ATP. The amount of EP formed was shown as the percentage of the control value obtained without F⁻, Be²⁺, and Al³⁺. The EP formation was not inhibited when the incubations were performed with Be²⁺ or Al³⁺ but without F⁻. The error bars show the S. D. of five independent experiments.