Differential contribution of two serine residues of wild type and constitutively active β₂‐adrenoceptors to the interaction with β₂‐selective agonists

Abstract

1 We have studied the di erence in receptor binding activity between partial and full b 2 -adrenoceptor agonists and the abilities of the agonists to interact with Ser 204 and Ser 207 in the ®fth transmembrane region of the b 2 -adrenoceptor, amino acid residues that are important for activation of the b 2 -adrenoceptor. (7)-isoprenaline) and b 2 -(83% and 74% of (7)-isoprenaline) adrenoceptors. 4 The a nities of full agonists, TA-2005 and (7)-isoprenaline, were markedly decreased by substitution of Ala for Ser 204 (S204A) of the b 2 -adrenoceptor, whereas this substitution slightly reduced the a nities of partial agonists, (+)-salbutamol and (+)-salmeterol. Although the a nities of full agonists for the S207A-b 2 -adrenoceptor were decreased, those of partial agonists for the S207A-b 2 -adrenoceptor were essentially the same as for the wild type receptor. 5 The constitutively active mutant (L266S, L272A) of the b 2 -adrenoceptor had an increased a nity for all four agonists. The a nities of full agonists were decreased by substitution of Ser 204 of the constitutively active mutant, whereas the degree of decrease was smaller than that caused by the substitution of the wild type receptor. Although the a nities of (+)-salbutamol and (+)-salmeterol for the S207A-b 2 -adrenoceptor were essentially the same as those for the wild type b 2 -adrenoceptor, the a nities of (+)-salbutamol and (+)-salmeterol for the constitutively active b 2 -adrenoceptor were decreased by substitution of Ser 207 . 6 These results suggest that Ser 204 and Ser 207 of the wild type and constitutively active b 2 -adrenoceptors di erentially interacted with b 2 -selective agonists.

Three-Dimensional Models for β-Adrenergic Receptor Complexes with Agonists and Antagonists

“…37,38 Through ligand-binding measurements for a number of -receptor chimeras and site-directed mutants, Kikkawa et al have determined that a single residue, Y308 in the extracellular end of TM7 in the 2 -receptor, is responsible for -receptor subtype selectivity for TA-2005. 39 This residue is a phenylalanine in 1 and 3 -receptors.…”

Structure-affinity profile of 8-hydroxycarbostyril-based agonists that dissociate slowly from the β2-adrenoceptor

“…This suggested that the 8-hydroxycarbostyril nucleus in conjunction with the side chain geminal methyls and phenyl group are contributing factors to the slow dissociation and low K i of 11a. It has been proposed that the hydroxyl and amido groups of 8-hydroxycarbostyril correspond to the pand m-hydroxyl groups of catecholamines, respectively, and may interact with the same serine residues in the β 2 AR (Yoshizaki et al 1976;Kikkawa et al 1997). Interestingly, replacement of the 8-hydroxycarbostyril of 11a with catechol (14) reduces the affinity of the latter by 48-fold.…”

Ser203 as well as Ser204 and Ser207 in fifth transmembrane domain of the human β2‐adrenoceptor contributes to agonist binding and receptor activation

“…The transfection procedure, membrane preparation, receptor binding assays, and cyclic AMP accumulation assays were performed as described previously (Kikkawa et al ., 1997b).…”