Table 2

Affinities of Ro 40-6129, Ro 41-0639, and Ro 41-3380 for wild-type (α₁β₂γ₂) and mutant receptors

Receptor	Accessible Surface Area	Ro 40-6129		Ro 41-0639		Ro 41-3380
Receptor	Accessible Surface Area	K_I	n	K_I-mut/ K_I-α β γ	K_I	n	K_I-mut/ K_I-α β γ	K_I	n	K_I-mut/ K_I-α β γ
		nM			nM			nM
αβγ	115, 140^2-a	2.6 ± 0.7	3	1.0	0.4 ± 0.2	3	1.0	1.9 ± 0.2	4	1.0
αβγ A79C	135	8.6 ± 1.1^2-160	3	3.3	2.5 ± 0.4^2-160	4	6.3	18 ± 6^2-160	5	9.5
αβγ A79L	170	7.3 ± 1.5^2-160	3	2.8	1.1 ± 0.4	3	2.8	328 ± 87^2-160	3	173
αβγ A79E	190	3.5 ± 0.6	3	1.3	1.9 ± 0.3^2-160	3	4.8	119 ± 20^2-160	3	63
αβγ A79R	225	4.3 ± 1	3	1.7	1.2 ± 0.2	3	3.0	501 ± 203^2-160	5	264
αβγ A79Y	230	27 ± 2^2-160	3	10	7.6 ± 3.4^2-160	3	19	192 ± 2^2-160	3	101
αβγ T81C	135	19 ± 4^2-160	3	7.3	1.2 ± 0.3^*	4	3.0	16 ± 3^2-160	5	8.4

K_I values were determined by displacement of [³H]flunitrazepam binding. Mutations at γ₂A79 are arranged in ascending order of accessible side-chain surface area (Å²; Chothia, 1976). Data represent mean ± S.E.M.

↵2-a Accessible surface areas for both alanine and threonine are reported, respectively.
n, number of independent experiments.
↵2-160 , P < 0.01, significantly different from wild-type receptors.