FIGURE 3.

Post-translational modifications in regulation of photosynthetic light reactions (Lower) and Calvin cycle (Upper). In light reactions, phosphorylation (P) of Photosystem (PS) II subunits D1, D2, CP43 and PsbH are involved in PSII repair cycle, while phosphorylation of light harvesting proteins (Lhcb) is required for state transitions. Tyr nitration (NO₂-Tyr), N-terminal and Lys acetylation (Ac-N and Ac-Lys, respectively) and sumoylation (SU) of various PSII, Cytochrome b₆f (Cyt b₆f) and PSI subunits have been detected. In Calvin cycle, the function of Rubisco is controlled by a multitude of PTMs, including phosphorylation, Tyr-nitration, acetylation, Lys methylation (Me-Lys), nitrosylation (NO) and glutathionylation (GSH). Additionally, several other enzymes functioning in the Calvin cycle and activation of Rubisco are targets of various PTMs. The subchloroplastic sites of the PTMs are not indicated in the figure. 3PG, 3-phosphoglycerate; 1,3BPG, 1,3-bisphosphoglycerate; G3P, glyceraldehyde 3-phosphate; DHAP, dihydroxyacetone phosphate; FBP, fructose 1,6-bisphosphate; F6P, fructose 6-phosphate; X5P, xylulose 5-phosphate; R5P, ribose 5-phosphate; Ru5P, ribulose 5-phosphate; RuBP, ribulose 1,5-bisphosphate; S7P, sedoheptulose 7-phosphate; SBP, sedoheptulose 1,7-bisphosphate; E4P, erythrose 4-phosphate. The modified proteins are indicated with colors, while the non-modified proteins are shown as transparent. See text for details.