Summary of EC₅₀s of concentration-response curves for L-Phe at different [Ca²⁺]_o.

The [Ca2+]i responses of HEK-293 cells transfected with CaSR or its mutants upon stepwise increases of L-Phe in the presence of 1.5 mM [Ca2+]o were recorded. For L173P and P221Q, the L-Phe induced intracellular change were also measured in the presence of a level of high [Ca2+]o corresponding to their EC50 values for the [Ca2+]o, specifically 15.0 mM [Ca2+]o for mutant L173P and 5.0 mM for P221Q. The results are shown in the brackets. The EC50s were calculated from the concentration-response curves fitted using the Hill equation. # indicates significance with respect to wild type CaSR, p<0.05 (ANOVA, Dunnett test); * indicates significance with respect to the corresponding mutants in the presence of 1.5 mM [Ca2+]o, p<0.05 (two-way ANOVA). Summary of EC50s of concentration-response curves for L-Phe at different [Ca2+]o.