Identification of protein-protein interactions involving the eIF4E binding proteins Caf20p and Eap1p on yeast via affinity purification and LC-MSMS.

There are multiple translational control pathways. These include pathways involving eIF4E binding proteins (4E-BPs), which inhibit translation by binding and sequestering the 5’ cap binding protein eIF4E away from its partner eIF4G. Saccharomyces cerevisiae has two 4E-BPs: Caf20p and Eap1p. Previous analyses had shown that each 4E-BP regulates different subsets of mRNAs. In order to assess whether binding different proteins caused their different regulatory role, we used tandem affinity purification followed by label-free mass spectrometry to compare the proteomes pulled-down with the TAP-tagged 4E-BPs, and the global proteome. These analyses point out that Caf20p and Eap1p share most interaction partners, including ribosomes, and that both bind several other RNA-binding proteins.