Rpb7 bind to Rpb4 to form a heterodimer. This complex is thought to interact with the nascent RNA strand during RNA polymerase II . This family includes the homologs from RNA polymerase I and III. In RNA polymerase I, Rpa43 is at least one of the subunits contacted by the transcription factor TIF-IA . The N terminus of Rpb7p/Rpc25p/MJ0397 has a SHS2 domain that is involved in protein-protein interaction .
The eukaryotic RNA polymerase subunits RPB4 and RPB7 form a heterodimer that reversibly associates with the RNA polymerase II core. Archaeal cells contain a single RNAP made up of about 12 subunits, displaying considerable homology to the eukaryotic RNAPII subunits. The RPB4 and RPB7 homologues are called subunits F and E, respectively, and have been shown to form a stable heterodimer. While the RPB7 homologue is reasonably well conserved, the similarity between the eukaryotic RPB4 and the archaeal F subunit is barely detectable [PUBMED:11741548].
Todone F, Brick P, Werner F, Weinzierl RO, Onesti S; , Mol Cell 2001;8:1137-1143.: Structure of an archaeal homolog of the eukaryotic RNA polymerase II RPB4/RPB7 complex. PUBMED:11741548 EPMC:11741548 .
Yuan X, Zhao J, Zentgraf H, Hoffmann-Rohrer U, Grummt I; , 0;0:1-2.: Multiple interactions between RNA polymerase I, TIF-IA and TAFI subunits regulate preinitiation complex assembly at the ribosomal gene promoter. PUBMED:12393749 EPMC:12393749 .
Anantharaman V, Aravind L;, Proteins. 2004;56:795-807.: The SHS2 module is a common structural theme in functionally diverse protein groups, like Rpb7p, FtsA, GyrI, and MTH1598/TM1083 superfamilies. PUBMED:15281131 EPMC:15281131.