FIG 2.

Analysis of MARV virion-associated VP30 phosphorylation by LC-MS/MS. (A) Purification of MARV for LC-MS/MS analysis. (B) MS/MS analysis of MARV VP30 conducted with Proteome Discoverer, version 1.4, and the SEQUEST search engine. Peptides were in-gel digested with trypsin, eluted, and subjected to MS analysis on a Thermo LTQ Orbitrap XL mass spectrometer. Shown is the sequence of VP30. Peptides identified with high and median probabilities are shown in green and blue, respectively, and the phosphorylated residues are shown with black asterisks. (C) Identified VP30 phosphopeptides. (D to F) MS/MS spectra of representative phosphorylated peptides from virion-derived MARV VP30: MQQPRHRsR, ARPPsTFNLSKPPPPPK, and SPQDcGsPSLSK, as indicated. Lowercase letters indicate phosphorylation (s) or alkylation (c). Color peaks indicate matched MS/MS fragments, whereby green indicates precursors, and blue and red indicate y and b ions, respectively.