A non-acidic method using hydroxyapatite and phosphohistidine monoclonal antibodies allows enrichment of phosphopeptides containing non-conventional phosphorylations for mass spectrometry analysis
Authored by K. Adam, S. Fuhs, J. Meisenhelder, A. Aslanian, J. Diedrich, J. Moresco, J. La Clair, J.R. Yates, and T. Hunter
Posted
July 3, 2019
Server
bioRxiv
Abstract
Four types of phosphate-protein linkage generate nine different phosphoresidues in living organisms. Histidine phosphorylation is a long-time established but largely unexplored post-translational modification, mainly because of the acid-lability of the phosphoramidate bonds. This lability means that standard phosphoproteomic methods used for conventional phosphate esters (phospho-Ser/Thr/Tyr) must be modified to analyze proteins containing the phosphoramidate-amino acids - phospho-His/Arg/Lys. We show that a non-acidic method allows enrichment of non-conventional phosphoresidue-containing peptides from tryptic digests of human cell lines, using hydroxyapatite binding and/or immobilized 1-pHis and 3-pHis monoclonal antibodies for enrichment. 425 unique non-conventional phosphorylation sites (i.e. pHis, pLys and pArg) were detected with a high probability of localization by LC-MS/MS analysis and identified using a customized MaxQuant configuration, contributing to a new era of study in post-translational modification and cell signaling in humans. This is the first fully non-acidic method for phosphopeptide enrichment which uses immunoaffinity purification and remains compatible with mass spectrometry analysis for a wider coverage of potential protein phosphorylation events.
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