Fig. 2.

Ca²⁺-binding-deficient CaM mutants increase the R₂₅₀/Ca²⁺. We co-expressed Ca_V2.2 with CaM and CaM mutants with binding deficiencies at the N-, C-, and both lobes (CaM₁₂, CaM₃₄, and CaM₁₂₃₄, respectively) in HEK293T cells. The currents were recorded at +30 mV using Ca²⁺ or Ba²⁺ as the charge carrier, and the R₂₅₀/Ca²⁺ and R₂₅₀/Ba²⁺ were analyzed. A. Schematic representation of the CaM and CaM mutants. B. Representative normalized current traces (each trace was normalized to the inward peak current) from cells expressing CaM or mutants. C. Average R₂₅₀/Ca²⁺ and R₂₅₀/Ba²⁺. The numbers on each column refer to the number of cells used in each group. Data are presented as the mean ± SEM and were analyzed by one-way ANOVA with Fisher's post hoc test. *: p < 0.05, **: p < 0.01, and ***: p < 0.001 compared to the same expression group using Ca²⁺ as the charge carrier. #: p < 0.05 and ##: p < 0.001 compared to the R₂₅₀/Ba²⁺ of the CaM group. D. Plot of R₂₅₀/Ca²⁺ against I₃₀/Ca²⁺. The R₂₅₀/Ca²⁺ of each cell in Fig. 2C was plotted against the I₃₀/Ca²⁺. The lines indicated the linear regression of each group.