Molecular fluorescent indicators are versatile tools for dynamic imaging of biological systems. We now report a class of indicators that are based on the chemigenetic combination of a synthetic ion-recognition motif and a protein-based fluorophore. Specifically, we have developed a calcium ion (Ca²⁺) indicator that is based on genetic insertion of circularly permuted green fluorescent protein into HaloTag protein self-labeled with a ligand containing the Ca²⁺ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid. We have demonstrated the versatility of this design by also developing a sodium ion (Na⁺) indicator using a crown-ether-containing ligand. This approach affords bright and sensitive ion indicators that can be applicable to cell imaging. This design can enable the development of chemigenetic indicators with ion or molecular specificities that have not been realized with fully protein-based indicators.

分子荧光指示剂是生物系统动态成像的多功能工具。我们现在报告了一类基于合成离子识别基序和基于蛋白质的荧光团的化学组合的指示剂。具体来说，我们开发了一种钙离子 (Ca ²⁺ ) 指示剂，该指示剂基于将循环排列的绿色荧光蛋白遗传插入到 HaloTag 蛋白中，该蛋白使用含有 Ca 2+ 螯合剂^1,2-双（2-氨基苯氧基）的配体进行自标记)乙烷-N , N , N ', N'-四乙酸。我们还通过开发钠离子 (Na ⁺) 指示剂使用含冠醚的配体。这种方法提供了可适用于细胞成像的明亮且灵敏的离子指示剂。这种设计可以开发具有离子或分子特异性的化学遗传指示剂，而这些指示剂尚未完全基于蛋白质的指示剂实现。