POLR3H, also as known as A1665 and RPC8, belongs to the eukaryotic RPB7/RPC8 RNA polymerase subunit family. POLR3H is DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. It plays a key role in sensing and limiting infection by intracellular bacteria and DNA viruses. POLR3H acts as nuclear and cytosolic DNA sensor involved in innate immune response.