Table 6. Functional Activity at 10 μM (Percent Activity in β-Arrestin-Recruitment TANGO Assaya Compared with Standard Agonist or Antagonist) at Human ORsa.
| DOR | KOR | MOR | |||
|---|---|---|---|---|---|
| no. | Ag (%) | Antag (%) | Antag (%) | Ag (%) | Antag (%) |
| 4 | –10.3 | 25.3 | 125 | –1.6 | 18.8 |
| 24 | 0.7 | 35.3 | 58.2 | 0.3 | –13.4 |
| 25 | –1.7 | –6.0 | 88.1 | –1.2 | 22.6 |
| 28 | –0.6 | 85.4 | 99.6 | 0.4 | 96.4 |
| 29 | –1.1 | 93.2 | 104.5 | 1.6 | 96.9 |
| 35 | –1.9 | 14.1 | 112.9 | 3.1 | 82.1 |
| 44 | 6.7 | 20.3 | 65.5 | 6.0 | –44.4 |
Determined by PDSP, using the Tango GPCR assays as described:42 the principle of the assay: receptor activation recruits a β-arrestin fusion protein connected to tobacco etch virus (TEV) protease to the activated OR. The cleavage by TEV protease releases the hybrid factor for transcription GAL4-VP16 from its position fused to the OR. The liberation of the transcription factor induces expression of the β-lactamase reporter gene.49 KOR agonist activity was not determined. Values are expressed as the mean ± SEM of one assay performed in duplicate. The following standard DOR, KOR, and MOR ligands were used for comparison: agonists (set as 100% activation at 10 μM) DAMGO 99, salvinorin A 109, and morphine 110, respectively. Reference antagonist used was naloxone 121 (set as 100% inhibition, at 10 μM), of the effects of corresponding agonist (nM): DOR, DALDE 97; KOR, 109 (3); MOR, 99 (300).