Receptor-G protein γ specificity:: γ11 shows unique potency for A1 adenosine and 5-HT1A receptors

被引:44
作者
Lim, WK
Myung, CS
Garrison, JC
Neubig, RR [1 ]
机构
[1] Univ Michigan, Dept Pharmacol, Ann Arbor, MI 48109 USA
[2] Univ Michigan, Dept Internal Med Hypertens, Ann Arbor, MI 48109 USA
[3] Univ Virginia, Hlth Sci Ctr, Dept Pharmacol, Charlottesville, VA 22908 USA
关键词
D O I
10.1021/bi010950c
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
G protein coupled receptors activate signal transducing guanine nucleotide-binding proteins (G proteins), which consist of an alpha subunit and a betay dimer. Whole cell studies have reported that receptors signal through specific beta gamma subtypes. Membrane reconstitution studies with the adenosine A(1) and alpha (2A) adrenergic receptors have reached a similar conclusion. We aimed to test the generality of this finding by comparing the gamma subtype specificity for four G(i)-coupled receptors: alpha (2A) adrenergic; A1 adenosine (A(1)-R); 5-hydroxytryptamine(1A) (5-HT1A-R); mu opioid. Membranes were reconstituted with G alpha (i1) and five gamma subtypes (dimerized to beta1). Using a sensitive alpha-beta gamma binding assay, we show that all recombinant beta gamma (except beta1 gamma1) had comparable affinity for alpha (i1). Using high affinity agonist binding as a measure of receptor-G protein coupling, beta gamma -containing gamma 11 was the most potent for A(1)-R and 5-HT1A-R (p < 0.05, one way ANOVA) while gamma7 was most potent for the other two receptors. gamma 11 was 3-8-fold more potent for the A(1)-R than were the other gamma subtypes. Also. gamma 11 was 2-8-fold more potent for A(1)-R than at the other receptors, suggesting a unique coupling specificity of the A(1)-R for gamma 11. In contrast, the discrimination by receptors for the other beta gamma subtypes (beta1 and gamma1, gamma2, gamma7, and gamma 10) was limited (2-3-fold). Thus the exquisite beta gamma specificity of individual receptors reported in whole cell studies may depend on in vivo mechanisms beyond direct receptor recognition of beta gamma subtypes.
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收藏
页码:10532 / 10541
页数:10
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