TABLE 1

The chimeric β₁/β₂-adrenoceptor constructs, the amino acid changes made, and where a stable cell line was made; receptor expression levels are given as fmol/mg protein

Constructs	Amino Acid Changes	Protein
		fmol/mg
β₁-WT		556 ± 39
β₁-TM1	L63I, L64V, A66S, L71A, A74F, V81T	372 ± 47
β₁-TM2	M98T, S102C, L110A, T117A, I118H, V119I, V120L	567 ± 58
β₁-TM3	L133F, V137I, L154V	1994 ± 214
β₁-TM4	G177V, L178I, V179I, C180L, T181M, A184I, I185V, A187G, V189T, L195Q, W199Y	233 ± 18
β₁-TM5	R222Q, V230I, C238V, A241V, L245S	359 ± 30
β₁-TM6	V332T, L342I, A343V, V345I, K347H, A348V, F349I	1207 ± 100
β₁-TM7	R357E, L358V, F359Y, V360I, F361L, F362L, L365I, A368V, A371G, I375L	2078 ± 133
β₁-A187G	A187G
β₁-V189T	V189T
β₁-L195Q	L195Q
β₁-W199Y	W199Y
β₁-TM4 stage 1	G177V, L178I, V179I
β₁-TM4 stage 2	G177V, L178I, V179I, C180L, T181M, A184I, I185V
β₁-TM4 stage 3	G177V, L178I, V179I, C180L, T181M, A184I, I185V, A187G
β₁-TM4 stage 4	G177V, L178I, V179I, C180L, T181M, A184I, I185V, A187G, V189T
β₁-TM4 stage 5	G177V, L178I, V179I, C180L, T181M, A184I, I185V, A187G, V189T, L195Q
β₁-V189T-L195Q	V189T, L195Q
β₁-V189T-W199Y	V189T, W199Y
β₁-L195Q-W199Y	L195Q, W199Y
β₁-V189T-L195Q-W199Y	V189T, L195Q, W199Y
β₁-W199A	W199A
β₁-W199D	W199D
β₁-W199F	W199F
β₁-W199K	W199K
β₁-W199L	W199L
β₁-W199N	W199N
β₂-WT		268 ± 25
β₂-TM1	I38L, V39L, S41A, A46L, F49A, T56V	138 ± 8
β₂-TM2	T73M, C77S, A85L, A92T, H93I, I94V, L95V	405 ± 41
β₂-TM3	F108L, I112V, V129L	1037 ± 113
β₂-TM4^{^a}	V152G, I153L, I154V, L155C, M156T, I159A, V160I, G162A, T164V, Q170L	458 ± 64
β₂-TM5	Q197R, I205V, V213C, V216A, S220L	849 ± 83
β₂-TM6	T281V, I291L, V292A, I294V, H296K, V297A, I298F	728 ± 58
β₂-TM7	E306R, V307L, Y308F, I309V, L310F, L311F, I314L, V317A, G320A, L324I	67 ± 5

↵^a Making the full change here (i.e., with Y174W) rendered the receptor nonfunctional (no binding and no functional responses). This chimera with 10 of the 11 amino acid substitutions was therefore used as the β₂-TM4 mutant.