Protein kinases and phosphatases of the plastid and their potential role in starch metabolism.

Phospho-proteomic studies have confirmed that phosphorylation is a commonmechanism to regulate protein function in the chloroplast, including the enzymes ofstarch metabolism. In addition to the photosynthetic machinery protein kinases (STN7and STN8) and their cognate protein phosphatases PPH1 (TAP38) and PBCP, multipleother protein kinases and phosphatases have now been localized to the chloroplast.Here, we build a framework for understanding protein kinases and phosphatases,their regulation, and potential roles in starch metabolism. We also catalog mappedphosphorylation sites on proteins of chloroplast starch metabolism to illustrate thepotential and mostly unknown roles of protein phosphorylation in the regulation of starchbiology.