Protein phosphorylation is a very important and frequent post-translational modification that can impact a protein's localization, stability, and whether or not it can dimerize or form stable bonds with other substances.
It is vital to pinpoint which amino acid in the protein’s primary structure is being phosphorylated in order to understand the functions of a phosphopeptide.
This is accomplished through phosphopeptide mapping, which involves digestion of a radioactively labeled protein, separation of phosphopeptide products, and finally analysis via high-performance liquid chromatography (HPLC) or mass spectrometry.
As modified self antigens, they are potentially immunogenic when compared to unmodified self proteins as the immune cells (T-cells) which recognise them are possibly not subject to central tolerance mechanisms.
This may contribute to the potential capability of phosophopeptides to serve as tumor antigens in the treatment of colorectal cancer.