RNA polymerases catalyse the DNA dependent polymerisation of RNA. Prokaryotes contain a single RNA polymerase compared to three in eukaryotes (not including mitochondrial and chloroplast polymerases). This domain, domain 7, represents a mobile module of the RNA polymerase. Domain 7 interacts with the lobe domain of Rpb2 (<db_xref db="INTERPRO" dbkey="IPR007642"/>) [<cite idref="PUB00002975"/>, <cite idref="PUB00008731"/>].