Pharmacological characterization of receptor-activity-modifying proteins (RAMPs) and the human calcitonin receptor
Pharmacological characterization of receptor-activity-modifying proteins (RAMPs) and the human calcitonin receptor
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DOI：
10.1016/s1056-8719(00)00074-5
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发表时间：
1999-12-01
影响因子：
1.9
通讯作者：
Chen, WJ
中科院分区：
文献类型：
--
作者：
Armour, SL;Foord, S;Chen, WJ
受体活性修饰蛋白 (RAMP) 是一个单跨膜结构域蛋白家族，对于降钙素基因相关肽 (CGRP) 受体的转运和配体特异性非常重要。在本报告中，我们描述了利用非洲爪蟾黑素细胞表达系统对与不同 RAMP 共表达的人降钙素受体 (hCTR) 的药理学特性进行了分析。我们发现 RAMP3 与人降钙素受体的共表达改变了 hCTR 与人降钙素 (hCAL) 和大鼠胰淀素的相对效力。相反，RAMP1 和 RAMP2 对 hCAL 或大鼠胰淀素的 hCTR 效力变化影响不大。当与 RAMPS 共表达时，hCTR 逆转了相对效力，对 hCAL 的敏感性降低了 3.5 倍，对大鼠胰岛淀粉样多肽的敏感性增加了 19 倍。 AC66 是一种反向激动剂，对 hCAL 和大鼠胰淀素产生明显的简单竞争性拮抗作用，如线性 Schild 回归所示。 RAMPS 共表达时，AC66 阻断大鼠胰岛淀粉样多肽的效力发生改变，但 hCAL 反应没有改变。在没有 RAMPS 的情况下，AC66 与 hCAL 的平均 pK(B) 为 9.4 +/- 0.3，在有 RAMPS 的情况下，AC66 与 hCAL 的平均 pK(B) 为 9.45 +/- 0.07。对于AC66对大鼠胰岛淀粉样多肽的拮抗作用，在没有RAMPS的情况下，pK(B)为9.25+/-0.15，在有RAMPS的情况下，pK(B)为8.2+/-0.35。这一发现表明，RAMPS 可能会改变降钙素受体的活性状态，从而产生一种新的“胰岛淀粉样多肽样”受体表型。无论新受体种类的生理学关联如何，共表达膜蛋白可以完全改变受体的激动剂和拮抗剂亲和力的发现对重组受体系统的筛选产生了影响。 (C) 2000 Elsevier Science Inc. 保留所有权利。
Receptor-activity-modifying proteins (RAMPs) are a family of single transmembrane domain proteins shown to be important for the transport and ligand specificity of the calcitonin gene-related peptide (CGRP) receptor. In this report, we describe the analysis of pharmacological properties of the human calcitonin receptor (hCTR) coexpressed with different RAMPs with the use of the Xenopus laevis melanophore expression system. We show that coexpression of RAMP3 with human calcitonin receptor changed the relative potency of hCTR to human calcitonin (hCAL) and rat amylin. RAMP1 and RAMP2, in contrast, had little effect on the change of hCTR potency to hCAL or rat amylin. When coexpressed with RAMPS, hCTR reversed the relative potency by a 3.5-fold loss in sensitivity to hCAL and a 19-fold increase in sensitivity to rat amylin. AC66, an inverse agonist, produced apparent simple competitive antagonism of hCAL and rat amylin, as indicated by linear Schild regressions. The potency of AC66 was changed in the blockade of rat amylin but not hCAL responses with RAMPS coexpression. The mean pK(B) for AC66 to hCAL was 9.4 +/- 0.3 without RAMPS and 9.45 +/- 0.07 with RAMPS. For the antagonism of AC66 to rat amylin, the pK(B) was 9.25 +/- 0.15 without RAMPS and 8.2 +/- 0.35 with RAMPS. The finding suggests that RAMPS might modify the active states of calcitonin receptor in such a way as to create a new receptor phenotype that is "amylin-like." Irrespective of the physiological association of the new receptor species, the finding that a coexpressed membrane protein can completely change agonist and antagonist affinities for a receptor raises implications for screening in recombinant receptor systems. (C) 2000 Elsevier Science Inc. All rights reserved.