This family includes the Rpb4 protein. This family also includes C17 (aka CGRP-RCP) is an essential subunit of RNA polymerase III. C17 forms a subcomplex with C25 [4] which is likely to be the counterpart of subcomplex Rpb4/7 in Pol II [3].

1: Structure of an archaeal homolog of the eukaryotic RNA polymerase II RPB4/RPB7 complex. Todone F, Brick P, Werner F, Weinzierl RO, Onesti S; Mol Cell 2001;8:1137-1143. PMID:11741548

2: An Rpb4/Rpb7-like complex in yeast RNA polymerase III contains the orthologue of mammalian CGRP-RCP. Siaut M, Zaros C, Levivier E, Ferri ML, Court M, Werner M, Callebaut I, Thuriaux P, Sentenac A, Conesa C; Mol Cell Biol. 2003;23:195-205. PMID:12482973

3: C25, an essential RNA polymerase III subunit related to the RNA polymerase II subunit RPB7. Sadhale PP, Woychik NA; Mol Cell Biol. 1994;14:6164-6170. PMID:8065349

4: Structural biology of RNA polymerase III: subcomplex C17/25 X-ray structure and 11 subunit enzyme model. Jasiak AJ, Armache KJ, Martens B, Jansen RP, Cramer P; Mol Cell. 2006;23:71-81. PMID:16818233