HeLa phosphoproteome regulated by PP2A related proteins

HeLa cells were treated with siRNAs of PP2A related proteins or with okadaic acid, in triplicates. Tryptic digests of extracted proteins were analyzed using a Q Exactive mass spectrometer, before and after TiO2 phosphopeptide enrichment. Data were searched with Mascot via Proteome Discoverer. For phosphorylation site localization, phosphoRS was enabled. In parallel, SpectraST searching was performed via Proteome Discoverer, against an in-house made spectral library of phosphopeptides simulated using SimPhospho software.