Proteomic Profiling of the TRAF3 Interactome Network Reveals a New Role for the ER-to-Golgi Transport Compartments in Innate Immunity

van Zuylen, Wendy J.; Doyon, Priscilla; Clément, Jean-François; Khan, Kashif Aziz; D'Ambrosio, Lisa M.; Dô, Florence; St-Amant-Verret, Myriam; Wissanji, Tasheen; Emery, Gregory; Gingras, Anne-Claude; Meloche, Sylvain; Servant, Marc J.

affinity purification and LC-MS/MS, followed by analysis with SAINT. FLAG-p115 was found to be associated with nine proteins (after filtering), including Sec16A and GM130 (also known as GOLGA2), an established physical partner of p115 [34] ( Figure 1D and Figure S1 ). The interaction of EGFP-Sec16A with Myc-p115 was further confirmed by co-immunoprecipitation experiments ( Figure 1E ). However, endogenous TRAF3 was not recovered in our FLAG-p115 analysis. This result may be explained by the fact that p115 has many higher-abundance interactors and/or is part of alternative complexes independent from TRAF3. However, overexpressed Myc-TRAF3 was recovered from FLAG-p115 complexes when the latter were immunoprecipitated from 293T cells co-expressing both constructs ( Figure 1F ). The TRAF3 interactome network identified by functional proteomics ( Figure S1B ) suggests the presence of at least a fraction of TRAF3 in close proximity to the Golgi network.