In-depth analysis of protein phosphorylation by multidimensional ion exchange chromatography and mass spectrometry

Protein phosphorylation controls fundamental biological functions that are often deregulated in disease. Therefore, system-level understanding of complex pathophysiological processes requires methods that can be used to profile and quantify protein phosphorylation as comprehensively as possible. Here we present a detailed protocol to enrich phosphopeptides from total cell lysates in a form amenable to downstream analysis by mass spectrometry. Using these techniques, we have detected several thousands of phosphorylation sites in the NIH-3T3 cell line.