A mechanism for regulation of chloroplast LHC II kinase by plastoquinol and thioredoxin

► A new model for regulation of chloroplast LHC II kinase by PQH2 and thioredoxin. ► PQH2 activates Stn7 by reducing its lumenal cysteines. ► The stromally-placed kinase domain of Stn7 contains a novel thioredoxin-like motif. ► The reduction of the cysteines in the stromal motif by thioredoxin inactivates Stn7.