Table 2

Ability of agonists to activate PI hydrolysis at native and mutant 5-HT_2A receptors

Drug	5-HT_2A	W76A	F125L	W200A	W336A	F339L	F340L	F365L	W367A	Y370A	F383A
Bufotenine
K _ACT(nm)	84 ± 2	65 ± 26	109 ± 128	881 ± 83^2-a	1838 ± 179^2-a	158 ± 96	1,900 ± 190^2-a	585 ± 271^2-a	N.D.	1346 ± 796^2-a	84 ±2
V _MAX (% 5-HT)	72 ± 1	27 ± 2	67 ± 20	11 ± 2^2-a	16 ± 2^2-a	75 ± 14	10.5 ± 1.4^2-a	30 ± 14^2-a		21 ± 2	72 ± 2
α-Methyl-serotonin
K _ACT(nm)	57 ± 14	241 ± 63^2-a		N.D.	3090 ± 836^2-a		N.D.	311 ± 133^2-a	14,140 ± 6810^2-a	3258 ± 900^2-a	117 ± 18
V _MAX (% 5-HT)	103 ± 13	31 ± 12^2-a		N.D.	23 ± 5^2-a		N.D.	100 ± 12	22 ± 18^2-a	59 ± 3^2-a	100 ± 3
5-HT
K _ACT (nm)	47 ± 13	91 ± 15	249 ± 110	2637 ± 439^2-a	716 ± 403^2-a	249 ± 110	7,200 ± 2000^2-a	118 ± 41	7100 ± 3100^2-a	14280 ± 960^2-a	43 ± 6
V _MAX (% 5-HT)	100	31 ± 10^2-a	100 ±7	3 ± 2^2-a	27 ± 2^2-a	100 (N = 2)	18 ± 3^2-a	32 ± 2^2-a	7 ± 1^2-a	9 ± 2^2-a	100 ±2
DOM
K _ACT (nm)	42 ± 16	166 ± 33^2-a		N.D.	180 ± 123		28,1000 ± 14,000	98 ± 26	2360 ± 1075^2-a	11,410 ± 599^2-a	67 ± 6
V_MAX (% 5-HT)	87 ± 4	42 ± 3^2-a		N.D.	21 ± 2^2-a		50 ± 3^2-a	56 (N = 2)	8 ± 1^2-a	9 ± 1^2-a	81 ± 2

Data represent mean ± standard deviation of computer-derived estimates for K _act andV _max values for experiments that have been replicated at least three times (except where noted).V _max values are expressed relative to 5-HT expression of native 5-HT_2A receptors. In a typical experiment, basal activity ranged from 200 to 400 cpm, whereas the maximum stimulation elicited by 5-HT was 6,000–10,000 cpm.

N.D., no activation of PI hydrolysis detected (>30% elevation over background).
↵2-a p < 0.05 versus native receptor (F test).