EC50 values (μm) and Hill coefficients for 5-HT activation of 234-Tyr mutant receptors using non-sense suppression (A) and [3H]granisetron binding affinities of Tyr mutants (B)
| A | ||
|---|---|---|
| 234- | EC50 ± SE | nH ± SE |
| Ala | 120 ± 9.43* | 2.43 ± 0.38 |
| Ser | 84.1 ± 5.60* | 2.54 ± 0.37 |
| Phe | 10.22 ± 0.80* | 1.92 ± 0.26 |
| Cha | NR | NR |
| 4-F-Phe | 4.11 ± 0.20* | 2.36 ± 0.19 |
| F3-Phe | NR | NR |
| F5-Phe | NR | NR |
| Tyr (WT) | 1.24 ± 0.05 | 2.89 ± 0.28 |
| mTyr | 7.42 ± 0.32* | 2.83 ± 0.32 |
| 4-Br-Phe | 1.78 ± 0.08 | 2.79 ± 0.32 |
| 4-Me-Phe | 1.13 ± 0.05 | 2.49 ± 0.22 |
| B | ||
|---|---|---|
| 234 | Kd (nm) | n |
| Phe | 1.3 ± 0.36 | 4 |
| Ala | NB | 5 |
| Ser | NB | 5 |
| Tyr (WT) | 0.32 ± 0.035 | 7 |
Asterisks indicate a significant difference (p<0.05) to Tyr (n = 3.6). Data in B are from Price and Lummis (2004). Substitutions have been approximately ordered by increasing size. NR, No response to concentrations of 5-HT up to 1 mm; NB, no binding; WT, wild type.