Beinborn M, Quinn S M, Kopin A S
Department of Medicine and Center for Gastroenterology Research on Absorptive and Secretory Processes, Tupper Research Institute, New England Medical Center, Tufts University School of Medicine, Boston, Massachusetts 02111, USA.
J Biol Chem. 1998 Jun 5;273(23):14146-51. doi: 10.1074/jbc.273.23.14146.
The development of non-peptide agonists for peptide hormone receptors would markedly expand the treatment options for a large number of diseases. However, difficulty in identifying non-peptide molecules which possess intrinsic activity has been a major obstacle in achieving this goal. At present, most of the known non-peptide ligands for peptide hormone receptors appear in standard functional assays to be antagonists. Here, we report that a constitutively active mutant of the human cholecystokinin-B/gastrin receptor, Leu325 --> Glu, offers the potential to detect even trace agonist activity of ligands which, at the wild type receptor isoform, appear to lack efficacy. The enhanced functional sensitivity of the mutant receptor enabled us to detect intrinsic activity of L-365,260, an established non-peptide antagonist for the cholecystokinin-B/gastrin receptor. Extending from this observation, we were able to demonstrate that minor structural modifications could convert L-365, 260 into either: (i) an agonist or (ii) an inverse agonist (attenuates ligand-independent signaling). The ability to confer functional activity to small non-peptide ligands suggests that the properties of endogenous peptide hormones can be mimicked, and even extended, by considerably less complex molecules.
开发用于肽激素受体的非肽激动剂将显著扩大大量疾病的治疗选择。然而，识别具有内在活性的非肽分子存在困难，这一直是实现这一目标的主要障碍。目前，在标准功能测定中，大多数已知的肽激素受体非肽配体表现为拮抗剂。在此，我们报告人胆囊收缩素B/胃泌素受体的组成型活性突变体Leu325→Glu，即使对于在野生型受体亚型中似乎缺乏效力的配体，也具有检测其微量激动剂活性的潜力。突变受体增强的功能敏感性使我们能够检测L-365,260的内在活性，L-365,260是一种已确立的胆囊收缩素B/胃泌素受体非肽拮抗剂。基于这一观察结果，我们能够证明，微小的结构修饰可以将L-365,260转化为：(i) 一种激动剂或 (ii) 一种反向激动剂（减弱非配体依赖性信号传导）。赋予小非肽配体功能活性的能力表明，内源性肽激素的特性可以被复杂度低得多的分子模拟甚至扩展。
