Aphosphoprotein is aprotein that isposttranslationally modified by the attachment of either a singlephosphate group, or a complexmolecule such as 5'-phospho-DNA, through a phosphate group. The targetamino acid is most oftenserine,threonine, ortyrosine residues (mostly ineukaryotes), oraspartic acid orhistidine residues (mostly inprokaryotes).[1]
Thephosphorylation of proteins is a major regulatory mechanism in cells.[2][3]
Phosphoproteins have been proposed asbiomarkers forbreast cancer.[4][2]
