Nucleolar RNA helicase 2 (DDX21)

RNA helicase that acts as a detector of the transcriptional status of both RNA polymerase (Pol) I and II: promotes ribosomal RNA (rRNA) processing and transcription from polymerase II (Pol II) (PubMed:25470060). Binds various RNAs, such as rRNAs, snoRNAs, 7SK and, at lower extent, mRNAs (PubMed:25470060).

In the nucleolus, localizes to rDNA locus, where it directly contrasts rRNAs and snoRNAs, and boosts rRNA transcription, processing and modification. Required for rRNA two'- O-methylation, possibly by promoting the recruitment of late- acting snoRNAs SNORD56 and SNORD58 with pre-ribosomal complexes (PubMed:25470060, PubMed:25477391).