The synthesis of phosphopeptides

Phosphorylation and dephosphorylation are key events in protein expression and regulation and in signal transduction. Phosphopeptides are very useful reagents for the study of these processes, and have been used to great advantage in the study of phosphatase substrate specificity, SH2 domain ligand specificity, and protein-protein interactions. Furthermore, the advent of cell-permeable peptide carriers, such as those from the antennapedia homeodomain and the HIV TAT transcription factor, has allowed the study of intracellular events, thus underscoring the utility of these reagents. In this paper we review methods for the synthesis of phosphopeptides with the emphasis on the preparation of phosphoamino acid building blocks.