Functions as a sorting adapter in different signaling pathways to facilitate downstream signaling leading to type I interferon induction (PubMed:16603631, PubMed:16757566, PubMed:25385819, PubMed:25825441). In TLR4 signaling, physically bridges TLR4 and TICAM1 and functionally transmits signal to TICAM1 in early endosomes after endocytosis of TLR4. In TLR2 signaling, physically bridges TLR2 and MYD88 and is required for the TLR2-dependent movement of MYD88 to endosomes following ligand engagement (PubMed:25385819). Involved in IL-18 signaling and is proposed to function as a sorting adapter for MYD88 in IL-18 signaling during adaptive immune response (PubMed:22685567). Forms a complex with RAB11FIP2 that is recruited to the phagosomes to promote the activation of the actin-regulatory GTPases RAC1 and CDC42 and subsequent phagocytosis of Gram-negative bacteria (PubMed:30883606). ; [Isoform 2]: Proposed to inhibit LPS-TLR4 signaling at the late endosome by interaction with isoform 1 thereby disrupting the association of isoform 1 with TICAM1. May be involved in TLR4 degradation in late endosomes.
