Table 4.

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.