THYLAKOID MEMBRANE-PROTEIN PHOSPHORYLATION IN CORRELATION WITH PHOTOSYNTHETIC MEMBRANE ACTIVATION

The phosphorylation of five E. gracilis thylakoid membrane polypeptides was studied, in isolated chloroplasts. Using [32P] labelling, in the light, we found that phosphorylation was inhibited by ethanol and DCMU. Inhibition curves were characteristic of photosynthetic inhibition. [γ-32P] ATP labelling was used to distinguish between two groups of phosphoproteins: the first one, includes protein I, II, V which require only ATP for phosphorylation while the second one includes protein III and IV whose phosphorylation is light-requiring. Phosphorylation of protein III and IV was inhibited by CCCP, NH4Cl and DCMU, and was reversible in the dark. © 1979.