RNA polymerase II
Surface model of the RNA polymerase II complex of baker's yeast (each of the 10 subunits colored differently), according to PDB 3G1G; RNA (left) and DNA (left + right) as a cartoon
RNA polymerase II (RNAP II, POL-II) , more precisely DNA-dependent RNA polymerase II core complex , is an enzyme complex ( polymerases ) that catalyzes the synthesis of ribonucleic acids (RNA) during the transcription of DNA in eukaryotes .
The POL-II in multicellular animals and thus also in humans is a protein complex of twelve subunits.
| protein | Gene name | AA | UniProt | comment |
|---|---|---|---|---|
| RPB1 | POLR2A | 1970 | P24928 | Catalytic centers ( zinc fingers , 2 Mg 2+ ) |
| RPB2 | POLR2B | 1174 | P30876 | Catalytic centers ( zinc fingers , together with RPB1: Mg 2+ ) |
| RPB3 | POLR2C | 275 | P19387 | Interacts with RPB11a |
| RPB4 | POLR2D | 142 | O15514 | Part of the RPB4-RPB7 sub-complex, binds single-stranded RNA / DNA |
| RPABC1 | POLR2E | 210 | P19388 | Also part of the pol-I and -III complexes |
| RPABC2 | POLR2F | 127 | P61218 | Also part of the pol-I and -III complexes |
| RPB7 | POLR2G | 172 | P62487 | Part of the RPB4-RPB7 sub-complex, binds single-stranded RNA / DNA |
| RPABC3 | POLR2H | 149 | P52434 | Also part of the pol-I and -III complexes |
| RPB9 | POLR2I | 125 | P36954 | Zinc fingers |
| RPB11-a | POLR2J | 117 | P52435 | |
| RPABC4 | POLR2K | 58 | P53803 | Also part of the pol-I and -III complexes |
| RPABC5 | POLR2L | 67 | P62875 | Also part of the pol-I and -III complexes |
Main reaction
The extension of the mRNA based on the model of the bound single-stranded DNA is catalysed by RNA polymerase, this example of a ribulose molecule, which is already part of the mRNA and uracil - nucleotide UTP :
+ 
→ 
+ PP i
The phosphate group of the UTP is esterified with the hydroxyl group of the ribulose of the mRNA . An elongated RNA is formed and diphosphate (PP i ) is split off.