Table 3.

EC₅₀ values (μm) and Hill coefficients for 5-HT activation of 153-Tyr mutant receptors (n = 3-6) (A) and [³H]granisetron binding affinities of Tyr mutants (B)

A
153-	EC₅₀ ± SE	n_H ± SE
Ala	120 ± 9.43^*	2.43 ± 0.38
Ser	84.1 ± 5.60^*	2.54 ± 0.37
Phe	22.5 ± 0.43^*	2.60 ± 0.11
4-F-Phe	19.7 ± 1.22^*	1.82 ± 0.14^*
F₅-Phe	(>500)
Tyr (WT)	1.15 ± 0.04	2.78 ± 0.20
mTyr	(>500)
4-Me-Phe	18.2 ± 0.48^*	2.48 ± 0.11
4-MeO-Phe	6.65 ± 0.27^*	1.98 ± 0.12^*

B
153-	K_d (nm)	n
Ala	3.62 ± 1.75^*	3
Ser	NB	6
Phe	0.90 ± 0.20	5
Tyr (WT)	0.32 ± 0.035	7

Data in B are from Price and Lummis (2004). Substitutions have been approximately ordered by increasing size. The asterisk indicates a significant difference (p<0.05) to Tyr. NB, No binding; WT, wild type.