Temperature-dependent binding of hydrophilic beta-adrenergic receptor ligands to intact human lymphocytes.
Temperature-dependent binding of hydrophilic beta-adrenergic receptor ligands to intact human lymphocytes.
复制标题
亲水性β-肾上腺素受体配体与完整人淋巴细胞的温度依赖性结合。
DOI：
10.1016/0024-3205(86)90330-9
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发表时间：
1986
期刊：
影响因子：
6.1
通讯作者：
Feldman,RD
中科院分区：
文献类型：
--
作者：
Thede-Reynolds,KR;Motulsky,HJ;Feldman,RD
已经描述了β-肾上腺素能受体激动剂和拮抗剂之间结合特性的重要差异。然而，这些观察结果是复杂的，因为大多数可用的拮抗剂比激动剂更亲脂。为了从亲脂性配体与亲水性配体的结合特征中分离出激动剂与拮抗剂的结合特征，我们研究了亲水性配体异丙肾上腺素（激动剂）和CGP-12177（拮抗剂）与完整人淋巴细胞中[125 I]碘吲哚酚结合的竞争。分析在13°C、25°C和37°C下进行的测定的竞争曲线，我们证明在较低温度下，异丙肾上腺素的IC 50降低，但CGP-12177没有降低。使用与异丙肾上腺素预孵育然后广泛洗涤的细胞，与异丙肾上腺素和CGP-12177的竞争曲线是双相的，并且其特征在于对两种亲水性配体具有低亲和力的受体群体的出现。此外，在较低的温度下，这些曲线的双相性被强调，其特征在于异丙肾上腺素和CGP-12177的低亲和力位点群体的表观KD分别增加了6倍和40倍。
Important differences in binding characteristics between agonists and antagonists of the β-adrenergic receptor have been described. However, these observations have been complicated since most available antagonists are much more lipophilic than agonists. In order to separate out those binding characteristics of agonist vs. antagonist from those characteristics of lipophilic vs. hydrophilic ligands, we have studied competition of the hydrophilic ligands isoproterenol (agonist) and CGP-12177 (antagonist) with [125I] iodopindolol binding in intact human lymphocytes. Analyzing competition curves from assays performed at 13°C, 25°C and 37°C we demonstrated that at lower temperatures there was a decrease in IC50for isoproterenol but not for CGP-12177. Using cells preincubated with isoproterenol then extensively washed, competition curves with both isoproterenol and CGP-12177 were biphasic, and characterized by the appearance of a population of receptors with a low affinity for both hydrophilic ligands. Furthermore, at lower temperatures the biphasic nature of these curves was accentuated and was characterized by a 6-fold and 40-fold increase in the apparent KDof a population of low affinity sites for isoproterenol and CGP-12177, respectively.