biostudies-literatureSugiura KMEXT | Japan Society for the Promotion of Science (JSPS)12091-12098https://www.ebi.ac.uk/biostudies/studies/S-EPMC6690705biostudies-literatureUnknown294(32)Thiol-based redox regulation via ferredoxin-thioredoxin (Trx) reductase/Trx controls various functions in chloroplasts in response to light/dark changes. Trx is a key factor of this regulatory system, and five Trx subtypes, including 10 isoforms, have been identified as chloroplast-localized forms in <i>Arabidopsis thaliana</i> These subtypes display distinct target selectivity, and, consequently, they form a complicated redox regulation network in chloroplasts. In this study, we developed a FRET-based sensor protein by combining CFP, YFP, and the N-terminal region of CP12, a redox-sensitive regulatory and Trx-targeted protein in chloroplasts. This sensor protein enabled us to monitor the redox change of chloroplast thioredoxin <i>in vivo</i>, and we therefore designated this protein "chanThe Journal of biological chemistryThe thioredoxin (Trx) redox state sensor protein can visualize Trx activities in the light/dark response in chloroplasts.PMC669070516H06556Sugiura KYokochi YFukaya YMihara SFu NYoshida KHisabori TfalseThe thioredoxin (Trx) redox state sensor protein can visualize Trx activities in the light/dark response in chloroplasts.Thiol-based redox regulation via ferredoxin-thioredoxin (Trx) reductase/Trx controls various functions in chloroplasts in response to light/dark changes. Trx is a key factor of this regulatory system, and five Trx subtypes, including 10 isoforms, have been identified as chloroplast-localized forms in <i>Arabidopsis thaliana</i> These subtypes display distinct target selectivity, and, consequently, they form a complicated redox regulation network in chloroplasts. In this study, we developed a FRET-based sensor protein by combining CFP, YFP, and the N-terminal region of CP12, a redox-sensitive regulatory and Trx-targeted protein in chloroplasts. This sensor protein enabled us to monitor the redox change of chloroplast thioredoxin <i>in vivo</i>, and we therefore designated this protein "chan2019-01-01T00:00:00Z2019 Aug2025-04-05T15:17:44.428Z2025-04-05T15:17:44.428ZS-EPMC66907053121727710.1074/jbc.RA119.00761610.1074/jbc.ra119.007616