Modifications of p53: competing for the lysines

The p53 tumour suppressor protein is subject to numerous post-translational modifications, which coalesce in various combinations and patterns to regulate its activity. In addition to a multitude of phosphorylated serines and threonines, many of the lysine residues in p53 can be modified to regulate activity, stability and subcellular localization of the protein. This complexity is amplified by the variety of modifications that can target the same lysine residue - often with opposing effects on p53 function.