(-)-1-(3,4-Dimethoxyphenetylamino)-3-(3,4-dihydroxy)-2- propanol [(-)-RO363] is a highly selective β1-adrenergic receptor (β1AR) agonist. To study the binding site of β1-selective agonist, chimeric β1/β2 and Ala-substituted β1ARs were constructed. Several key residues of β1AR [Leu110 and Thr117 in transmembrane domain (TMD) 2], and Phe359 in TMD 7] were found to be responsible for β1-selective binding of (-)-RO363, as determined by competitive binding. Based on these results, we built a three-dimensional model of the binding domain for (-)-RO363. The model indicated that TMD 2 and TMD 7 of β1AR form a binding pocket; the methoxyphenyl group of N-substituent of (-)-RO363 seems to locate within the cavity surrounded by Leu110, Thr117, and Phe359. The amino acids Leu110 and Phe359 interact with the phenyl ring of (-)-RO363, whereas Thr117 forms hydrogen bond with the methoxy group of (-)-RO363. To examine the interaction of these residues with β1 AR in an active state, each of the amino acids was changed to Ala in a constitutively active (CA)-β1AR mutant. The degree of decrease in the affinity of CA-β1AR for (-)-RO363 was essentially the same as that of wild-type β1AR when mutated at Leu110 and Thr117. However, the affinity was decreased in Ala-substituted mutant of Phe359 compared with that of wild-type β1AR. These results indicated that Leu110 and Thr117 are necessary for the initial binding of (-)-RO363 with β1-selectivity, and interaction of Phe359 with the N-substituent of (-)-RO363 in an active state is stronger than in the resting state.
|ジャーナル||Journal of Pharmacology and Experimental Therapeutics|
|出版ステータス||出版済み - 2002|
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