TABLE 2

Receptor interaction parameters obtained from BRET saturation curves performed at room temperature (RT) or at 37°C, in the absence of agonist, or 10 min after agonist stimulation (10 μM)

BRETmax is the maximum BRET signal and BRET50 represents the ratio of the density (femtomoles per milligram) of acceptor and donor receptors (acceptor/donor) yielding 50% maximum BRET signal. Data presented as mean ± S.E.M.; n = 3, each measured in duplicate.

Acceptor/Donor Interactions BRETmax BRET50
MOR-GFP/MOR-Rluc MOR-MOR
RT 0.16 ± 0.01 2.7 ± 0.5
37°C 0.17 ± 0.01 3.5 ± 0.6
+ DAMGO 0.16 ± 0.01 2.6 ± 0.4
DOR-GFP/DOR-Rluc DOR-DOR
RT 0.42 ± 0.01 1.8 ± 0.1
37°C 0.40 ± 0.01 1.7 ± 0.2
+ SNC80 0.41 ± 0.02 1.6 ± 0.1
KOR-GFP/KOR-Rluc KOR-KOR
RT 0.18 ± 0.01 2.5 ± 0.2
37°C 0.16 ± 0.01 2.0 ± 0.2
+ BRL 52537 0.17 ± 0.01 2.1 ± 0.3
MOR-GFP/DOR-Rluc MOR-DOR, RT 0.34 ± 0.01 3.7 ± 0.2
DOR-GFP/MOR-Rluc 0.12 ± 0.01 3.2 ± 0.5
MOR-GFP/KOR-Rluc MOR-KOR, RT 0.14 ± 0.02 2.4 ± 0.7
KOR-GFP/MOR-Rluc 0.22 ± 0.01 3.8 ± 0.6
DOR-GFP/KOR-Rluc DOR-KOR, RT 0.18 ± 0.01 2.5 ± 0.3
KOR-GFP/DOR-Rluc 0.27 ± 0.01 1.8 ± 0.2