information:extraction, stylistic:style_transfer
RNA polymerase

RNA polymerase II (Pol II) is responsible for the transcription of all mRNAs, some snRNAs, siRNAs, and all miRNAs. Many Pol II transcripts exist transiently as single strand precursor RNAs (pre-RNAs) that are further processed to generate mature RNAs. For example, precursor mRNAs (pre-mRNAs) are extensively processed before exiting into the cytoplasm through the nuclear pore for protein translation.