PHOTOSYSTEM-II CORE PHOSPHORYLATION HETEROGENEITY AND THE REGULATION OF ELECTRON-TRANSFER IN HIGHER-PLANTS - A REVIEW

Phosphorylation influences the association of proteins which leads to heterogeneous photosystem II core populations upon separation of solub ilised photosystem II particles by isoelectrofocusing. In this brief r eview, through a summary of the properties of the isolated heterogeneo us photosystem II complexes, a model on the function of core phosphory lation is presented. An observed consequence of phosphorylation is a m odification of the Q(B) pocket concerning herbicide and quinone bindin g activity, suggesting that it could be a mechanism of electron transf er regulation. Moreover, a main effect of phosphorylation is seen at t he level of core protein assembly within stacked regions of higher pla nts with direct consequences on protein turnover and response to stres s conditions. In conclusion, core phosphorylation seems to explain in part the functional heterogeneity of photosystem II seen in vivo.