What does RNA polymerase contain?

RNA polymerase (RNAP) is a large complex molecule made up of multiple protein subunits. The structure and function of prokaryotic RNA polymerase differs slightly from the eukaryotic RNAP.

Prokaryotes have only one type of RNA polymerase that transcribes all types of RNA. This prokaryotic form of RNAP is made up of four subunits.

Eukaryotes have 5 types of RNA polymerase, each of which has a different composition and function. RNA polymerase in eukaryotes may have 8 or more subunits. Each RNA polymerase type has a different number of subunits.

All RNA polymerases contain metal cofactors, in particular magnesium and zinc, which help facilitate the transcription process.