The calcitonin and amylin receptors (CTR and AMY receptors) are the drug targets for osteoporosis and diabetes treatment, respectively. Salmon calcitonin (sCT) and pramlintide were developed as peptide drugs that activate these receptors. However, next-generation drugs with improved receptor binding profiles are desirable for more effective pharmacotherapy. The extracellular domain (ECD) of CTR was reported as the critical binding site for the C-terminal half of sCT. For the screening of high-affinity sCT analog fragments, purified CTR ECD was used for fluorescence polarization/anisotropy peptide binding assay. When three mutations (N26D, S29P, and P32HYP) were introduced to the sCT(22–32) fragment, sCT(22–32) affinity for the CTR ECD was increased by 21-fold. CTR was reported to form a complex with receptor activity-modifying protein (RAMP), and the CTR:RAMP complexes function as amylin receptors with increased binding for the peptide hormone amylin. All three types of functional AMY receptor ECDs were prepared and tested for the binding of the mutated sCT(22–32). Interestingly, the mutated sCT(22–32) also retained its high affinity for all three types of the AMY receptor ECDs. In summary, the mutated sCT(22–32) showing high affinity for CTR and AMY receptor ECDs could be considered for developing the next-generation peptide agonists.

中文翻译：

---

靶向降钙素家族受体胞外域的高亲和力降钙素类似物片段的开发

降钙素和胰淀素受体（CTR 和 AMY 受体）分别是骨质疏松症和糖尿病治疗的药物靶点。鲑鱼降钙素 (sCT) 和普兰林肽被开发为激活这些受体的肽药物。然而，对于更有效的药物治疗，需要具有改进的受体结合谱的下一代药物。据报道，CTR 的细胞外结构域 (ECD) 是 sCT 的 C 端一半的关键结合位点。为了筛选高亲和力 sCT 类似物片段，使用纯化的 CTR ECD 进行荧光偏振/各向异性肽结合测定。当三个突变（N26D、S29P 和 P32HYP）被引入 sCT(22-32) 片段时，sCT(22-32) 对 CTR ECD 的亲和力增加了 21 倍。据报道，CTR 与受体活性修饰蛋白 (RAMP) 形成复合物，CTR:RAMP 复合物作为胰淀素受体发挥作用，与肽激素胰淀素的结合增加。制备了所有三种类型的功能性 AMY 受体 ECD，并测试了突变 sCT(22-32) 的结合。有趣的是，突变的 sCT(22-32) 也保留了对所有三种类型的 AMY 受体 ECD 的高亲和力。总之，突变的 sCT(22-32) 对 CTR 和 AMY 受体 ECD 具有高亲和力，可考虑用于开发下一代肽激动剂。