Table 1 Potency (pEC₅₀) and maximal response (E_max) of β-arrestin1/2 recruitment to WT and phosphorylation-deficient MOR mutants.

NA, not available.

MOR		β-Arrestin1				β-Arrestin2
		BRET		β-Gal		BRET		β-Gal
		pEC₅₀	E_max (% of WT DAMGO)	pEC₅₀	E_max (% of WT DAMGO)	pEC₅₀	E_max (% of WT DAMGO)	pEC₅₀	E_max (% of WT DAMGO)
WT	DAMGO	6.05 ± 0.06	100	5.82 ± 0.07	100	6.28 ± 0.04	100	5.94 ± 0.03	100
WT	Morphine	—	—	—	—	6.12 ± 0.05	33.57 ± 2.18	—	—
TSST-4A	DAMGO	6.10 ± 0.06	91.59 ± 1.56	5.86 ± 0.05	36.33 ± 6.79^	6.36 ± 0.02	94.08 ± 3.76	5.58 ± 0.05	56.73 ± 7.61^
TSST-4A	Morphine	—	—	—	—	5.85 ± 0.14	29.21 ± 4.11	—	—
S375A	DAMGO	5.89 ± 0.07	36.20 ± 6.27^	6.71 ± 0.13	32.20 ± 5.73^	6.30 ± 0.01	71.73 ± 6.47^	6.08 ± 0.18	49.36 ± 16.95^
S375A	Morphine	—	—	—	—	6.37 ± 0.14	17.31 ± 0.90^	—	—
STANT-3A	DAMGO	—	—	NA	NA	6.20 ± 0.06	56.26 ± 1.81^	NA	NA
STANT-3A	Morphine	—	—	NA	NA	6.40 ± 0.08	14.76 ± 1.66^	NA	NA
TREHPSTANT-4A	DAMGO	—	—	5.95 ± 0.48	28.47 ± 7.18^	NA	NA	5.72 ± 0.05	42.55 ± 6.31^
TREHPSTANT-4A	Morphine	—	—	—	—	NA	NA	—	—
11S/T-A	DAMGO	—	—	8.27 ± 1.74	23.46 ± 2.33^	6.16 ± 0.02	41.90 ± 5.48^	6.08 ± 0.17	43.73 ± 5.16^
11S/T-A	Morphine	—	—	—	—	6.29 ± 0.08	15.92 ± 1.67^	—	—

^Significance compared to WT (P < 0.01) by two-way ANOVA with Dunnett’s multiple comparison test.