Abstract：
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 (Ca2+i) and suppress the G12/13 and ERK1/2 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.
摘要：
人类钙敏感受体（CaSR）在体内可感知钙离子浓度，是一类重要的药物靶标。受体的突变会导致钙稳态紊乱，包括高钙血症和低钙血症。这里,从骆驼中产生了127个CaSR靶向纳米抗体，并进一步鉴定了4种具有抑制功能的纳米抗体。在这些纳米抗体中，NB32能有效抑制细胞内钙离子(Ca2+i)的动员,抑制CaSR下游的G12/13和ERK1/2信号通路。此外，它增强了钙解剂作为负变构调节剂（NAM）的抑制作用。我们确定了复合物的结构，发现NB32与CaSR的LB2（配体结合2）结构域结合，以防止两个原聚体的LB2结构域相互作用，从而稳定CaSR的非活性状态。
