Light, redox state, thylakoid-protein phosphorylation and signaling gene expression

Two recent publications concerning the chloroplast membrane-protein phosphorylation and state transition might lead to further progress in the elucidation of the mechanism and role of this process. A thylakoid-bound protein TSP9 is released to the chloroplast matrix upon redox-dependent stepwise phosphorylation of three threonine sites and might signal redox-dependent gene transcription. The state-transition process and phosphorylation of the light-harvesting complex II require the activity of a novel protein kinase Stt7.