FIGURE 2.

Calmodulin binding to immobilized PMCA. A, human erythrocyte PMCA at an immobilization level of ∼1000 RU was stabilized on the sensor surface in C₁₂E₁₀ micelles. Immediately after immobilization, a buffer containing 0.005% C₁₂E₁₀ was injected. Calmodulin was injected in the range 1.8–15 nm in a buffer composed of 20 mm MOPS-KOH (pH 7.2 at 25 °C), 120 mm KCl, 1 mm MgCl₂, 0.005% C₁₂E₁₀, and 70 μm Ca²⁺ at a flow rate of 30 μl/min for 60 s. B, nonlinear analysis of the binding response obtained in the SPR assays was performed using a 1:1 interaction fit. The K_d values that best fit the experimental data were 1.6 ± 0.3 nm.