Agonist interactions at hepatic alpha 1- and beta-adrenergic receptors: affinity-state regulation by guanine nucleotides and temperature.
Agonist interactions at hepatic alpha 1- and beta-adrenergic receptors: affinity-state regulation by guanine nucleotides and temperature.
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肝α1-和β-肾上腺素能受体的激动剂相互作用：鸟嘌呤核苷酸和温度的亲和状态调节。
DOI：
10.1021/bi00371a074
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发表时间：
1986
期刊：
影响因子：
2.9
通讯作者：
Graham,RM
中科院分区：
文献类型：
--
作者：
Schwarz,KR;Carter,EA;Homcy,CJ;Graham,RM
摘要：我们在不同的实验条件下研究了激动剂与（a）完整肝细胞，（B）破裂的大鼠肝细胞膜，和（c）洗涤剂溶解制剂的α-和β-肾上腺素能受体的结合特性，着重于激动剂受体的不同“状态”以及温度和鸟嘌呤核苷酸对这些状态的调节。虽然在37 ℃下用溶解的制剂进行的研究中，激动剂与两种受体亚型仅低亲和力结合是明显的，但在完整细胞和膜制剂中均观察到激动剂的双相竞争曲线;大多数位点具有低亲和力。在膜制剂中，不可水解的GTP类似物Gpp（NH）p引起激动剂竞争曲线的一次平移和高亲和力结合的损失。这些结果与鸟嘌呤核苷酸结合蛋白参与α-和β-肾上腺素能信号转导途径是一致的。当在4 C下进行竞争研究时，受体位点主要存在于高亲和力构型中，在完整的细胞和膜中，以及可溶性制剂中。与在37 ℃下进行的研究相反，在4 ℃下用膜纯化进行的研究中没有证明Gpp（NH）p诱导的向较低亲和力状态的转化。因此，α 1-和β-肾上腺素能受体的高亲和力状态在4 ℃下在完整细胞、膜和可溶性制剂中稳定。在37 ℃下孵育后，随后在4 ℃下孵育无法恢复激动剂的高亲和力结合。如先前对于β-肾上腺素能受体所报道的[Weiland，G.一、Minnemann，K. P.，& Molinoff，P. B.（1979）Nature（伦敦）281，114-117]，激动剂亲和力的温度变化幅度与肾上腺素能药剂对α-肾上腺素能受体的功能功效相关（激动剂>部分激动剂>拮抗剂），因此似乎反映了激动剂诱导的受体结合位点的构象变化本身。
Revised Manuscript Received August 20, 1986 abstract: We investigated the binding characteristics of agonists to a¡-and/3-adrenergic receptors of (a) intact liver cells,(b) brokenrat liver cell membranes, and (c) detergent-solubilized preparations under varying experimental conditions, focusing on the different “states” of the receptor for agonists and the regulation of these states bytemperature and guanine nucleotides. While only low-affinity binding of agonists to both receptor subtypes was evident in studies performed at 37 C with solubilized preparations, biphasic competition curves for agonists were observed in both intact cells and membrane preparations; the majority of sites were of low affinity. In membrane preparations, the nonhydrolyzable GTP analogue Gpp (NH) p caused a rightward shift of agonist competition curves and a loss of high-affinity binding. These results are consistent with the involvement of guanine nucleotide binding proteins in both a¡-and/3-adrenergic transduction pathways. When competition studies were performed at 4 C, receptor sites existed predominantly in the high-affinity configuration, in intact cells and membranes, as well as in soluble preparations. In contrast to the studies conducted at 37 C, no Gpp (NH) p-induced conversion to the lower affinity state could be demonstrated in studies performed with membrane preparationsat 4 C. Thus, the high-affinity state of a,-and/3-ad-renergic receptors is stabilized at 4 C in intact cells, membranes, and soluble preparations. After incubations had been performed at 37 C, high-affinity binding of agonists could not be restored by subsequent incubation at 4 C. As previously reported for the/3-adrenergic receptor [Weiland, G. A., Minnemann, K. P., & Molinoff, P. B.(1979) Nature (London) 281, 114-117], the magnitude of the temperatureshift in agonist affinity correlated with the functional efficacy of adrenergic agents at a¡-adrenergic receptors (agonist> partial agonist> antagonist) and thus seems to reflect an agonist-induced conformational change at the receptor binding site, per se.