Domain-specific interaction between DYRK1a and TRAF3. (A) Schematic summary of TRAF3 and its truncation mutants, depicting the ring finger (RF), zinc finger (ZF), and TRAF (TRAF-N and TRAF-C) domains and indicating their DYRK1a-binding function based on the CoIP results from panel B. (B) CoIP analysis of DYRK1a interaction with TRAF3 mutants using whole-cell lysates of HEK293 cells transfected with the indicated expression vectors (A). Cell lysates were also subjected to direct immunoblotting to monitor expression of TRAF3 mutants and DYRK1a (B). (C) Schematic representation depicting the domains of DYRK1a and its mutants and their ability to bind TRAF3 (based on CoIP results of D and E). (D-E) CoIP analysis of TRAF3 interaction with DYRK1a mutants using whole-cell lysates of HEK293 cells transfected with the indicated expression vectors (C). Cell lysates were also subjected to direct immunoblotting to monitor expression of DYRK1a mutants and TRAF3 (D,E). (F) CoIP assays to analyze the interaction of endogenous TRAF3 and DYRK1a in nontreated (NT) or BAFF-stimulated WT B cells. Nontreated TRAF3-BKO B cells were used as negative control.