<P> The prominent role of protein phosphorylation in biochemistry is illustrated by the huge body of studies published on the subject (as of March 2015, the MEDLINE database returns over 240,000 articles, mostly on protein phosphorylation). </P> <P> Phosphorylation of sugars is often the first stage of their catabolism . It allows cells to accumulate sugars because the phosphate group prevents the molecules from diffusing back across their transporter . Phosphorylation of glucose is a key reaction in sugar metabolism because many sugars are first converted to glucose before they are metabolized further . </P> <P> The chemical equation for the conversion of D - glucose to D - glucose - 6 - phosphate in the first step of glycolysis is given by </P> <Dl> <Dd> D - glucose + ATP → D - glucose - 6 - phosphate + ADP </Dd> </Dl>

Where does the phosphate group come from in phosphorylation