Enhances the ATPase activity of DHX15 by acting like a brace that tethers mobile sections of DHX15 together, stabilizing a functional conformation with high RNA affinity of DHX15. Involved in the constitutive silencing of the interferon beta promoter, independently of the virus-induced signals, and in the inhibition of the basal and cytokine-induced iNOS promoter activity. Also involved in the regulation of IL-8 transcription. May also act as a DNA-binding transcription regulator: interacts with a specific negative regulatory element (NRE) 5'-AATTCCTCTGA-3' to mediate transcriptional repression of certain NK-kappa-B responsive genes. Interacts with NF-kappa-B. Interacts with XRN2. Interacts (via G-patch domain) with DHX15; promoting the RNA helicase activity of DHX15.