To identify proteins that differentially interact with carboxylated and non-carboxylated MAVS, we overexpressed Flag-tagged WT or 4A mutant (D53A, E70A, E80A, and D83A) forms of hMAVS in 293T cells and analyzed the interactors using immunoprecipitation followed by mass spectrometry (MS). Cell lysates were subjected to immunoprecipitation with anti-FLAG antibodies, and the immunoprecipitated proteins were subsequently analyzed by LC-MS/MS.