Phosphorylation-specific MS/MS scoring for rapid and accurate phosphoproteome analysis.

TitlePhosphorylation-specific MS/MS scoring for rapid and accurate phosphoproteome analysis.
Publication TypeJournal Article
Year of Publication2008
AuthorsPayne SH, Yau M, Smolka MB, Tanner S, Zhou H, Bafna V
JournalJ Proteome Res
Date Published2008 Aug
KeywordsAlgorithms, Bayes Theorem, Models, Statistical, Phosphopeptides, Phosphoproteins, Phosphorylation, Probability, Proteome, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Schizosaccharomyces, Schizosaccharomyces pombe Proteins, Software, Tandem Mass Spectrometry

The promise of mass spectrometry as a tool for probing signal-transduction is predicated on reliable identification of post-translational modifications. Phosphorylations are key mediators of cellular signaling, yet are hard to detect, partly because of unusual fragmentation patterns of phosphopeptides. In addition to being accurate, MS/MS identification software must be robust and efficient to deal with increasingly large spectral data sets. Here, we present a new scoring function for the Inspect software for phosphorylated peptide tandem mass spectra for ion-trap instruments, without the need for manual validation. The scoring function was modeled by learning fragmentation patterns from 7677 validated phosphopeptide spectra. We compare our algorithm against SEQUEST and X!Tandem on testing and training data sets. At a 1% false positive rate, Inspect identified the greatest total number of phosphorylated spectra, 13% more than SEQUEST and 39% more than X!Tandem. Spectra identified by Inspect tended to score better in several spectral quality measures. Furthermore, Inspect runs much faster than either SEQUEST or X!Tandem, making desktop phosphoproteomics feasible. Finally, we used our new models to reanalyze a corpus of 423,000 LTQ spectra acquired for a phosphoproteome analysis of Saccharomyces cerevisiae DNA damage and repair pathways and discovered 43% more phosphopeptides than the previous study.

PubMed URL
Alternate TitleJ. Proteome Res.
PubMed ID18563926