RNA polimerases eucarióticas

Eukaryotes have three different RNA Polymerases: RNA polymerase I, II, and III.  They are structurally similar to one another and share common features with prokaryotic RNA polymerases, however, they transcribe different classes of RNA.

RNA Polymerase I transcribes most of the ribosomal RNA genes while RNA Polymerase III transcribes tRNA genes, some snRNA, and other small RNA genes.

The majority of protein-encoding RNA genes are transcribed by RNA polymerase II.

The carboxy-terminal domain of the RNA Polymerase II serves as a binding site for several transcription factors that regulate its enzymatic activity. The binding of these factors depends on the phosphorylation pattern of this domain.