Ptotein phosphorylation plays an important role in signal transduction and regulation. In the past decade, numerous research found out there were different kinds of protein kinases and protein phosphatases in plant cell. One of their main function is regulating activity of metabolic enzymes. In this paper, by using ATP to treat crude exact of apple fruit and observing the effect on several metabolic enzymes, we identified four of them might be regulated by protein phosphorylation: sucrose phosph...