TABLE 1.

G_q, G_s, and β-arrestin signaling of the WT NK1 receptor and mutant forms with Ala substitution in positions AsnI:18 (1.50), GluII:10 (2.50), SerIII:15Ala (3.39), TrpVI:13 (6.48), SerVII:12 (7.45), ThrVII:13 (7.46), AsnVII:16 (7.49), and TyrVII:20 (7.53) and Asp substitution in position GluII:10 (2.50)

The constructs were expressed in transiently transfected COS-7 cells (G_q and G_s) and CHOK1 cells (β-arrestin). The E_max values are expressed as percentage of the ligand-induced signaling for the WT NK1 receptor. Values are shown ± S.E. Comparison is between constitutive activity of WT NK1 and the mutant receptors (p < 0.05). ns = not significant.

Construct	IP3					cAMP				β-Arrestin2
	Expression level	n	EC50 (nm)	Emax	n	Constitutive activity	EC50 (nm)	Emax	n	EC50 (nm)	Emax	n
NK1 WT	1	8	0.31 ± 0.11	100	7	1.7 ± 1.4	0.62 ± 0.18	100	5	0.06 ± 0.01	100	8
AsnI:18Ala (1.50)	0.81 ± 0.07	3			3	9.3 ± 6a			4			4
GluII:10Ala (2.50)	0.56 ± 0.05	4			3	10.8 ± 6.7b			4	0.29 ± 0.03	20 ± 3.4	6
GluII:10Gln	1.31 ± 0.09	6	0.72 ± 0.25	38.6 ± 2.5	3	37.7 ± 4.6c			3	0.46 ± 0.25	98.06 ± 11.2	4
GluII:10Asp	1.49 ± 0.09	4	0.35 ± 0.12	85.2 ± 6.3	4	12.0 ± 6.6ns	20.3 ± 9.6	60.9 ± 6.5	4			3
SerIII:15Ala (3.39)	0.85 ± 0.05	3	0.42 ± 0.11	113 ± 5.3	6	37.4 ± 6.1c	1.29 ± 0.35	156 ± 17.7	6	0.07 ± 0.02	157 ± 21.0	10
TrpVI:13Ala (6.48)	0.73 ± 0.05	3			3		0.95 ± 0.43	14.0 ± 4.9	4			4
SerVII:12Ala (7.45)	0.93 ± 0.06	6	0.17 ± 0.06	35.0 ± 6.7	4	4.2 ± 2.1ns			5	0.03 ± 0.007	45.8 ± 4.5	6
ThrVII:13Ala (7.46)	0.84 ± 0.07	4	0.58 ± 0.13	133.4 ± 9.4	4	13.9 ± 4.4d	0.23 ± 0.08	85.5 ± 4.8	4	0.08 ± 0.04	95.2 ± 5.7	6
AsnVII:16Ala (7.49)	0.90 ± 0.06	5	0.35 ± 0.07	76.7 ± 8.1	5				4	0.23 ± 0.07	74.8 ± 8.9	6
TyrVII:20Ala (7.53)	0.78 ± 0.07	3			3				5	0.05 ± 0.02	9.3 ± 2.0	4

^a p = 0.0009.

^b p = 0.0015.

^c p < 0.0001.

^d p = 0.0108.