Neuroscience Drug Discovery, Johnson & Johnson Pharmaceutical Research & Development, LLC, 3210 Merryfield Row, San Diego, CA 92121, USA.
Eur J Pharmacol. 2011 Sep 30;667(1-3):120-8. doi: 10.1016/j.ejphar.2011.05.074. Epub 2011 Jun 12.
Orexin receptor antagonists are being investigated as therapeutic agents for insomnia and addictive disorders. In this study the interactions between the orexin receptors (orexin 1 receptor and orexin 2 receptor), orexin peptides, and small molecule orexin antagonists were explored. To study these phenomena, a variety of mutant orexin receptors was made and tested using receptor binding and functional assays. Domains of the two orexin receptors were exchanged to show the critical ligand binding domains for orexin peptides and representative selective orexin receptor antagonists. Results from domain exchanges between the orexin receptors suggest that transmembrane domain 3 is crucially important for receptor interactions with small molecule antagonists. These data also suggest that the orexin peptides occupy a larger footprint, interacting with transmembrane domain 1, the amino terminus and transmembrane domain 5 as well as transmembrane domain 3. Transmembrane domain 3 has been shown to be an important part of the small molecule binding pocket common to rhodopsin and β2-adrenergic receptors. Additional orexin receptor 2 point mutations were made based on the common arrangement of receptor transmembrane domains shown in the G-protein coupled receptor crystal structure literature and the impact of orexin 2 receptor residue threonine 135 on the ligand selectivity of the 2 orexin receptors. These data support a model of the orexin receptor binding pocket in which transmembrane domains 3 and 5 are prominent contributors to ligand binding and functional activity. The data also illustrate key contact points for ligand interactions in the consensus small molecule pocket of these receptors.
食欲素受体拮抗剂被作为失眠和成瘾障碍的治疗药物进行研究。在这项研究中，研究了食欲素受体（食欲素 1 受体和食欲素 2 受体）、食欲素肽和小分子食欲素拮抗剂之间的相互作用。为了研究这些现象，制备了多种突变的食欲素受体，并使用受体结合和功能测定进行了测试。交换了两种食欲素受体的结构域，以显示食欲素肽和代表性选择性食欲素受体拮抗剂的关键配体结合结构域。食欲素受体之间结构域交换的结果表明，跨膜结构域 3 对于受体与小分子拮抗剂的相互作用至关重要。这些数据还表明，食欲素肽占据了更大的足迹，与跨膜结构域 1、氨基末端和跨膜结构域 5 以及跨膜结构域 3 相互作用。已经表明，跨膜结构域 3 是与视紫红质和β2-肾上腺素能受体共同的小分子结合口袋的重要组成部分。根据 G 蛋白偶联受体晶体结构文献中显示的受体跨膜结构域的常见排列以及食欲素 2 受体残基苏氨酸 135 对 2 种食欲素受体配体选择性的影响，对食欲素受体 2 进行了额外的点突变。这些数据支持了食欲素受体结合口袋的模型，其中跨膜结构域 3 和 5 是配体结合和功能活性的主要贡献者。这些数据还说明了这些受体共识小分子结合口袋中配体相互作用的关键接触点。
