Phosphomimetics

Within cells, proteins are commonly modified at serine, tyrosine and threonine amino acids by adding a phosphate group.

For example, aspartic acid can be considered chemically similar to phospho-serine, due to it also carrying a negative charge.

Therefore, when an aspartic acid replaces a serine, it is a phosphomimetic of phospho-serine and can imitate the protein always in its phosphorylated form.

For example, aspartate mutants were successfully used to probe the biological function of the phosphorylation of a threonine residue of a ribosomal protein both in vivo[6] and in vitro[7] to investigate a gain-of-function mutation on a kinase that is related to Parkinson's disease.

[8] This approach is in particularly useful as up to three serine residues can be phosphoylated on the said protein,[8] and hence phosphomimetic mutants are useful to probe the function of the individual phosphorylation.