Control of Translation by Regulation of Protein Phosphorylation and Dephosphorylation

The activity of a seemingly exponentially increasing number of well characterized, specific enzymes and enzyme systems has been shown to be regulated by phosphorylation and dephosphorylation of their constituent peptides. Depending on the specific enzyme system, increased phosphorylation may cause either a decrease or an increase in enzymatic activity. Cognately with this change in enzymatic activity, a large number of phosphorylated peptides can be detected in extract from intact cells or cell lysates. Subtle to dramatic changes in the phosphorylation state of a single given target protein may be brought about by a variety of components or conditions, such as hormones and growth factors, camp, temperature and nutrients or virus infection that affect the biochemistry and physiology of intact cells. These types of observations have led to the hypothesis that protein phosphorylation and dephosphorylation reactions constitute a primary regulatory mechanism in eukaryotic cells.