This is the C-terminal domain of DNA-directed RNA polymerase III subunit RPC5 (POLR3E). PolIII is a complex consisting of 17 subunits and transcribes small RNAs, such as 5S rRNA and tRNA, that is involved in innate immune system as it senses viral DNA to produce non-self RNA polymerase III transcripts, which induce type I interferon and NF-Kappa-B. RPC5 forms a subcomplex with RPC4 which is close to the polymerase active centre that enables open promoter complex formation and facilitates termination and reinitiation. Mutations in this subunit are associated with impaired induction of type I IFN and increased susceptibility to viral infections [1].

1: A mutation in POLR3E impairs antiviral immune response and RNA polymerase III. Ramanathan A, Weintraub M, Orlovetskie N, Serruya R, Mani D, Marcu O, Stepensky P, Weisblum Y, Djian E, Shaag A, Revel-Vilk S, Fried I, Kotler M, Rouvinski A, Wolf D, Elpeleg O, Jarrous N; Proc Natl Acad Sci U S A. 2020;117:22113-22121. PMID:32843346