. 2016 Apr;89(4):457–466. doi: 10.1124/mol.115.101808

TABLE 3.

G-protein activation by dopamine and norepinephrine mediated by D2LR, D2SR, D3R, D4.2R, D4.4R, and D4.7R involving different Giα/o subtypes

Results were obtained from G protein activation-BRET experiments in HEK-293T cells transiently transfected with different Gαi-RLuc8 subtypes (Gαi1, Gαi2, Gαi3, Gαo1, Gαo2) and γ₂-mVenus in cells expressing different D₂-like receptors. Data were fit by nonlinear regression to a sigmoidal dose–response relationship against the agonist concentration. The EC₅₀ and E_max values are the mean ± S.E.M. of 5 to 18 experiments performed in triplicate. E_max values are expressed as 1000 × [BRET_max − BRET_basal].

Gα Subunit	Receptor	Dopamine		Norepinephrine		NE/DA (EC₅₀)
Gα Subunit	Receptor	EC₅₀ (nM)	E_max	EC₅₀ (nM)	E_max	NE/DA (EC₅₀)
Gαi1	D2LR	393 ± 43	19 ± 1	3609 ± 549	17 ± 1	9.2
	D2SR	161 ± 24^a	30 ± 1^a	987 ± 171^a	26 ± 1^a	6.1
	D3R	12 ± 3^a	15 ± 1	83 ± 33^a	15 ± 1	6.9
	D4.2R	18 ± 5^a	17 ± 1	116 ± 28^a	16 ± 2	6.4
	D4.4R	21 ± 6^a	22 ± 1	215 ± 31^a	20 ± 1	10.2
	D4.7R	26 ± 5^a	25 ± 2^b	229 ± 44^a	19 ± 1	8.8
Gαi2	D2LR	177 ± 46	21 ± 1	1765 ± 391	24 ± 4	10
	D2SR	92 ± 10^b	41 ± 2^a	1280 ± 309	39 ± 2^c	14
	D3R	ND	ND	ND	ND	—
	D4.2R	24 ± 6^a	37 ± 3^a	340 ± 69^c	31 ± 5	14
	D4.4R	19 ± 2^a	37 ± 4^a	134 ± 30^c	35 ± 2^b	7
	D4.7R	28 ± 8^c	45 ± 3^a	285 ± 46^c	47 ± 3^a	10.2
Gαi3	D2LR	132 ± 34	26 ± 2	1198 ± 160	26 ± 3	9.1
	D2SR	52 ± 8^a	40 ± 2^a	379 ± 103^a	40 ± 2^c	7.3
	D3R	3.6 ± 0.6^a	16 ± 1^a	49.4 ± 13^a	17 ± 1^b	13.7
	D4.2R	21 ± 7^a	29 ± 2	316 ± 70^a	30 ± 6	15
	D4.4R	12 ± 3^a	42 ± 5^a	476 ± 116^a	34 ± 3	39.7
	D4.7R	15 ± 2^c	38 ± 3^b	398 ± 102^a	39 ± 4^b	26.5
Gαo1	D2LR	182 ± 42	35 ± 2	534 ± 67	31 ± 2	2.9
	D2SR	24 ± 4^b	36 ± 1	159 ± 26^b	36 ± 2	6.6
	D3R	2 ± 0.3^b	22 ± 1^b	33 ± 11^b	21 ± 2	16.5
	D4.2R	197 ± 45	53 ± 3^c	408 ± 118	54 ± 4^a	2.1
	D4.4R	225 ± 44	57 ± 3^a	403 ± 78	54 ± 3^a	1.8
	D4.7R	228 ± 38	60 ± 4^a	557 ± 114	58 ± 4^a	2.4
Gαo2	D2LR	227 ± 41	64 ± 1	727 ± 53	55 ± 2	3.2
	D2SR	49 ± 14^a	64 ± 2	298 ± 68^a	60 ± 3	6.1
	D3R	3 ± 0.4^a	33 ± 2^a	49 ± 19^a	30 ± 3^a	16.3
	D4.2R	36 ± 16^a	72 ± 6	81 ± 26^a	61 ± 5	2.3
	D4.4R	50 ± 14^a	69 ± 4	275 ± 55^a	63 ± 3	5.5
	D4.7R	128 ± 51^b	63 ± 5	122 ± 36^a	57 ± 5	0.95

ND, not determined; NE/DA, ratio between EC₅₀ values of norepinephrine and dopamine.

^{^a}

P < 0.001 compared with D2LR (one-way analysis of variance, followed by post hoc Newman-Keuls test).

^{^b}

P < 0.05 compared with D2LR (one-way analysis of variance, followed by post hoc Newman-Keuls test).

^{^c}

P < 0.01 compared with D2LR (one-way analysis of variance, followed by post hoc Newman-Keuls test).