Method for the Quantitative Detection of Isoforms of Translation Initiation Factors 4E in Potato Leaf Tissues Using Multiple Reaction Monitoring

Potato, like other Solanaceae plants, have a small family of eukaryotic translation initiation factors 4E (eIF4E), including four proteins eIF4E-1, eIF4E-2, eIF(iso)4E, and the novel cap-binding protein (nCBP). These factors play roles in the process of the post-transcriptional regulation of gene expression. The eIF4Es are also used by numerous RNA viruses to synthesize their proteins. The quantitative detection of eIF4Es at the proteome level yields data about their abundances and the involvement of each factor in the process of translation initiation under normal and stress conditions. To quantify eIF4Es, we have developed a mass spectrometry protocol for the detection of isoforms in potato S. tuberosum leaf tissues by multiple reaction monitoring (MRM) assay. As a result, we have detected all potato eIF4Es and determined their amounts with the most abundant protein, eIF4E-1.