Nanobodies as negative allosteric modulators for human calcium sensing receptor

• Published in: Biochemical and biophysical research communications 2024-02, Vol.695, p.149401, Article 149401
• Main Authors: Cui, Qianqian, Wang, Lu, Wang, Haonan, Chen, Xiaochen, Han, Li, Geng, Tengjie, Kou, Yongjun, Zhang, Wenqing, Dai, Mei, Qiao, Huarui, Sun, Zengchao, Li, Lingyun, Lan, Zhongyun, Xu, Hongxi, Xu, Jiaqiang, Dai, Yuanyuan, Geng, Yong
• Format: Article
• Language: English
• ISSN: 0006-291X; 1090-2104; 1090-2104
• DOI: 10.1016/j.bbrc.2023.149401

Human calcium sensing receptor (CaSR) senses calcium ion concentrations in vivo and is an important class of drug targets. Mutations in the receptor can lead to disorders of calcium homeostasis, including hypercalcemia and hypocalcemia. Here, 127 CaSR-targeted nanobodies were generated from camels, and four nanobodies with inhibitory function were further identified. Among these nanobodies, NB32 can effectively inhibit the mobilization of intracellular calcium ions (Ca ) and suppress the G and ERK signaling pathways downstream of CaSR. Moreover, it enhanced the inhibitory effect of the calcilytics as a negative allosteric modulator (NAM). We determined the structure of complex and found NB32 bound to LB2 (Ligand-binding 2) domain of CaSR to prevent the interaction of LB2 domains of two protomers to stabilize the inactive state of CaSR.