RNA polymerase II makes the mRNA that ribosomes read. It grips duplex DNA in a cleft, unwinds one turn, then pairs the template strand with a growing RNA chain. A bridge helix and a trigger loop sit at the active site and check each incoming nucleotide. After each bond the enzyme moves one base along the template, and the new RNA leaves through a separate groove.
- Where
- Nucleus of all eukaryotes. Bacteria use a five-subunit-type RNA polymerase with the same core.
- Power
- The nucleoside triphosphate substrate itself. Pyrophosphate release drives the chain forward.
~3.8 kb per minute
Elongation rate in human cells
18