RIP1 is recruited to the activated TLR receptor by binding to TICAM1(TRIF) via its RHIM motif, followed by its polyubiquitination. Polyubiquitination is possibly mediated by TRAF6 that is also recruited to TICAM1 (Cusson-Hermance N et al. 2005). Other E3-ubiquitin ligases - cIAP1 and cIAP2 - have been reported to promote polyubiquitination of RIP proteins (Bertrand MJM et al. 2011).
RIP3 was shown to inhibit TRIF-induced NFkB activation in dose-dependent manner when overexpressed in HEK293T cells by competing with TRIF to bind RIP1 (Meylan E et al. 2004).