[1] The ncRNA that is involved in rDNA silencing is known as pRNA and has been shown to originate from a spacer promoter located upstream of the pre-ribosomal RNA transcription start site.

Once this ncRNA is transcribed it is processed to form a 150–250 nucleotide long RNA molecule and overlaps the rDNA promoter region.

Several studies have shown that pRNA is vital in the recruitment and localization of the chromatin remodelling complex which is needed for gene silencing.

This conformational change may allow TIP5 to interact with other proteins that are required for NoRC function but this needs to be confirmed by further studies.

[2] These studies confirmed that pRNA has a role gene silencing by targeting chromatin remodelling complex to a rDNA gene promoters where both pRNA sequence and structure are crucial for its function.