STING was reported to mediate TBK1-dependent activation of transcription factor IRF3 (Zhong B et al. 2008, Tanaka and Chen 2012). Both TBK1 and IRF3 can directly interact with STING through its C-terminal region (Tanaka & Chen 2012). A construct of human STING containing only 39 amino acid residues of its C-terminus (341 to 379) was sufficient to activate IRF3 in cytosolic extracts of HeLa cells. Further mutagenesis studies showed, that two residues, Ser366 and Leu374, within the C-terminal tail of STING were required for IRF3 binding and phosphorylation, but were dispensable for TBK1 binding and activation (Tanaka & Chen 2012). Thus, STING is thought to function as a scaffold to recruit cytosolic TBK1 and IRF3, which results in TBK1-dependent phosphorylation of IRF3. Importantly, though both STING monomers and dimers can bind TBK1, only STING dimers activates Type I IFN (Ouyang et al. 2012). The nucleotide binding domain and leucine-rich repeat-containing (NLR) protein NLRC3 interacts with STING and TBK1, reducing STING-TBK1 association and reduces the trafficking of STING to the perinuclear region, leading to decreased activation of innate immune cytokines (Zhang et al. 2014).