Table 1. Summary of cellular responses of HEK293 cells transiently transfected with WT CaSR or disease related mutants.

Mutants	EC50[Ca2+]O		Hill coefficient		Frequency
	w/o L-Phe	with 5 mM L-Phe	w/o L-Phe	with 5 mM L-Phe	w/o L-Phe	with 5 mM L-Phe
WT	3.0±0.2	1.9±0.3*	3.7±0.3	5.0±0.7*	1.3±0.1	2.1±0.1*
L173F	1.9±0.2#	1.6±0.1	3.3±0.1	3.7±0.3	1.7±0.1#	1.9±0.1
P221L	2.0±0.1#	1.7±0.1	3.2±0.2	2.8±0.2	1.6±0.1#	1.8±0.2
L173P (Phase 1)	3.8±0.3	3.1±0.2	3.3±0.6	2.5±0.2	1.3±0.1	1.8±0.2*
L173P (Phase 2)	13.0±0.3	12.2±0.2*	3.6±0.4	5.8±0.3
P221Q	5.2±0.4#	3.7±0.4*	2.4±0.4#	4.1±0.7*	1.5±0.1	2.2±0.1*

The average levels of [Ca²⁺]_o at which cells started to exhibit [Ca²⁺]_i oscillations were recorded for WT or each mutant CaSR. For the oscillation frequencies in the absence of L-Phe, peaks per minute were measured at the level of [Ca²⁺]_o at which more than 50% cells started to oscillate; when L-Phe was added, frequencies were recorded at the same [Ca²⁺]_o as their counterparts without L-Phe. Specifically, the frequencies of WT was measured at 3.0 mM [Ca²⁺]_o, at 2.5 mM [Ca²⁺]_o for L173F and P221L; at 15.0 mM [Ca²⁺]_o for L173Pand at 5.0 mM [Ca²⁺]_o for P221Q. Curve-fitting was performed using the Hill equation. The data were obtained from three experiments for each construct. Values are means ± S.E. EC₅₀ and Hill numbers obtained from the cell population assay by fitting plots using the Hill equation. ^# indicates significance with respect to wild type CaSR in the absence of L-Phe, p<0.05 (ANOVA, Dunnett test); ^* indicates significance with respect to the corresponding mutants in the absence of L-Phe, p<0.05 (two-way ANOVA).