Advances in Separation and Enrichment Approach of Phosphoproteome Researches

Protein phosphorylation is one of the most important reversible modifications in nature; it is involved in many cellular processes such as the proliferation, differentiation, cellular signaling, transcriptional and translational regulation, protein–protein interactions, subcellular localization, and degradation of proteins. Hence, phosphorylation is one of the most common and best characterized posttranslational modifications of cellular proteins. The detection of phosphopeptides remains challenging because of the low abundance of phosphoproteins. The enrichment of phosphoproteins and phosphopeptides is one of the important methods to improve the MS response of phosphopeptide signals. This review summarizes the methods currently available for the enrichment of phosphoproteins and phosphopeptides, including immunoprecipitation enrichment method, kinase-selective enrichment method, affinity enrichment method, chemical modification method, affinity chromatography, and matrix-assisted laser desorption/ionization (MALDI) plates specific enrichment method.