The effects of amino acid mutations of recombinant CB1 receptors on the displacement of [3H]WIN55,212-2 or [3H]CP55,940 by cannabinoid receptor ligands
Data represent the mean and corresponding 95% confidence limits of at least three independent experiments performed in triplicate. Values reported are nanomolar except where indicated. Competition experiments for the S7.39A mutant were carried out against [3H]WIN55,212-2, because no binding was observed with [3H]CP55,940 on this mutant. On the S2.60A mutant, competition binding were performed against [3H]CP55,940. Statistical analysis was performed by comparing the Ki of the mutant receptor to that of the wild-type CB1 receptors (*, P < 0.05) using the Student t test to determine the level of significance.
WIN55,212-2 | SR141716A | CP55,940 | HU210 | AM4056 | |
|---|---|---|---|---|---|
| [3H]WIN55,212-2 | |||||
| WT | 13.9 (7.2-27) | 18.4 (8.2-41) | 10.0 (1.3-74) | 0.45 (0.07-3) | 0.37 (0.12-1) |
| S7.39A | 7.7 (2-28) | 14.2 (7.8-25) | —a | 45.7* (12-180) | 20.6* (5.6-76) |
| [3H]CP55,940 | |||||
| WT | 15.9 (9-28) | 7.2 (3.2-16) | 1.4 (0.8-2.4) | 0.38 (0.25-0.58) | 0.63 pM (0.1-3.6) |
| S2.60A | 17.1 (5-59) | 22.8 (13-40) | 1.2 (0.2-8) | 0.66 (0.13-0.34) | 0.5 pM (0.04-5) |
↵ a At 10 μM CP55,940, 40% displacement was observed.