Possible endogenous agonist mechanism for the activation of secretin family G protein-coupled receptors
Possible endogenous agonist mechanism for the activation of secretin family G protein-coupled receptors
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DOI：
10.1124/mol.105.021840
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发表时间：
2006-07-01
影响因子：
3.6
通讯作者：
Miller, Laurence J.
中科院分区：
文献类型：
--
作者：
Dong, Maoqing;Pinon, Delia I.;Miller, Laurence J.
G蛋白偶联受体的B类家族包含几个潜在的重要药物靶点，但我们对配体结合和受体活化的分子基础的理解仍然不完整。虽然这些受体的富含半胱氨酸的二硫键氨基末端结构域被认为是一个关键作用，但配体对接和由此产生的构象变化的详细见解尚不清楚。我们假设，结合天然配体这个域的结果在构象变化，暴露的内源性配体与受体的身体相互作用，激活it. In这项工作中，我们研究了是否合成肽对应的候选区域之间的第一和第三保守的半胱氨酸可以作为激动剂。事实上，这种肽是一种弱有力但完全有效的激动剂，在分泌素受体携带细胞中刺激浓度依赖性cAMP反应。当肽长度从30减少到5时，这种效果得以维持，并且最终，三个残基集中在保守残基Asp（49）上。通过二氨基丙酸接头环化和氨基末端脂肪酸酰化增强激动剂效力。环肽的两端显示与受体的跨膜区段6的顶部相互作用，使用在每个末端具有光不稳定的苯甲酰基-苯丙氨酸的探针。对该家族的另外两个成员，血管活性肠多肽1型和降钙素受体也进行了类似的观察。这些数据可能提供了一个独特的分子机制和新的线索，为开发小分子激动剂作用于这个生理上重要的受体家族内的潜在药物靶点。
The class B family of G protein-coupled receptors contains several potentially important drug targets, yet our understanding of the molecular basis of ligand binding and receptor activation remains incomplete. Although a key role is recognized for the cysteine-rich, disulfide-bonded amino-terminal domain of these receptors, detailed insights into ligand docking and resultant conformational changes are not clear. We postulate that binding natural ligands to this domain results in a conformational change that exposes an endogenous ligand which interacts with the body of the receptor to activate it. In this work, we examined whether a synthetic peptide corresponding to a candidate region between the first and third conserved cysteines could act as an agonist. Indeed, this peptide was a weakly potent but fully efficacious agonist, stimulating a concentration-dependent cAMP response in secretin receptor-bearing cells. This effect was maintained as the peptide length was reduced from 30 to 5, and ultimately, three residues focused on the conserved residue Asp(49). The agonist potency was enhanced by cyclization through a diaminopropionic acid linker and by amino-terminal fatty acid acylation. Both ends of the cyclic peptide were shown to interact with the top of transmembrane segment 6 of the receptor, using probes with a photolabile benzoyl-phenylalanine on each end. Analogous observations were also made for two other members of this family, the vasoactive intestinal polypeptide type 1 and calcitonin receptors. These data may provide a unique molecular mechanism and novel leads for the development of small-molecule agonists acting at potential drug targets within this physiologically important receptor family.