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 (PubMed:12381793). 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 (PubMed:12381793). Also involved in the regulation of IL-8 transcription (PubMed:12381793). 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 (PubMed:10562553).