POLR2H is an essential and highly conserved subunit of RNA polymerase II which is shared by the other 2 eukaryotic DNA-directed RNA polymerases， I and III. The three eukaryotic RNA polymerases are complex multisubunit enzymes which play a vital role in the transcription of nuclear genes. POLR2H encodes an essential and highly conserved subunit of RNA polymerase II which is shared by the other two eukaryotic DNA-directed RNA polymerases， I and III.
