Competition binding profiles performed to determine observed differences in radioligand [3H]SQ29,548 binding by the mutant TPα receptors
| Cells | Ki Values | |
|---|---|---|
| [U46619] | [SQ29,548] | |
| (× 106 M ± S.E.) | (× 108 M ± S.E.) | |
| TPα | 0.77 ± 0.25 | 1.34 ± 0.13 |
| TPαN4–Q4 | 0.41 ± 0.07 | 0.76 ± 0.16 |
| TPαN16–Q16 | 0.57 ± 0.09 | 1.60 ± 0.20 |
| TPαN4,N16–Q4,Q16 | 0.24 ± 0.15 | 1.56 ± 0.35 |
For competition binding studies, binding of [3H]SQ29,548 (20nM, 50.4 Ci/mmol) was carried out on HEK 293 cells transiently transfected with the plasmids coding for the wild–type TPα or mutant TPαN4–Q4, TPαN16–Q16and TPαN4,N16–Q4,Q16 receptors in the presence of the competitor ligands: U46619 (10−8–10−5 M) or SQ29,548 (10−9–10−6 M). Nonspecific binding was determined in the presence of excess non-labeled SQ29,548 (10μM). Radioligand binding data were analyzed using INPLOT 4 computer program (GraphPad Software Inc.) to determine the individualKr values for U46619 (× 106 M ± S.E.,n = 4) and SQ29,548 (× 108 M ± S.E.,n = 4).