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.

To further confirm the localization of TRAF3 to the Golgi apparatus, we next treated the cells with nocodazole. Microtubule depolymerization is known to result in the reorganization of the Golgi complex into characteristic mini-stacks, which appear as punctate structures throughout the cell [40] . Nevertheless, FLAG-TRAF3 was detected to colocalize with GM130 and Myc-p115 in cells treated with nocodazole ( Figure S3 , panels 1, 2 and 3). Treatment with brefeldin A (BFA), leads to relocalization of the components of the cis-Golgi matrix to cytoplasmic punctate structures (also called remnants) that appear close to ERES [41, 42] . GM130 and p115 are cis-Golgi proteins, which are known to be relocalized to these remnants [41] . FLAG-TRAF3 was also relocated to cytoplasmic remnants upon BFA treatment, where it co-localized with GM130 and Myc-p115 ( Figure S3 , panels 4 and 5). Altogether, results from our pharmacological experiments and confocal microscopy strongly suggest that TRAF3 localized to ER-to-Golgi transport compartments, where it tightly associates [43, 44] .