Rpc25 is a strongly conserved subunit of RNA polymerase III and has homology to Rpa43 in RNA polymerase I, Rpb7 in RNA polymerase II and the archaeal RpoE subunit. Rpc25 is required for transcription initiation and is not essential for the elongating properties of RNA polymerase III [1].

1: Rpc25, a conserved RNA polymerase III subunit, is critical for transcription initiation. Zaros C, Thuriaux P; Mol Microbiol 2005;55:104-114. PMID:15612920