Ribosomal RNA
Ribosomal RNA genes (rDNA) encodes for ribosomal RNA (rRNA) that constitutes the majority of the ribosome. These genes are not constitutively expressed and a mechanism of gene silencing is put in place to suppress rDNA gene expression when the ribosome isn’t required. Gene silencing of rDNA requires binding of the chromatin remodelling complex, NoRC to a non-coding RNA (ncRNA) molecule that is complementary to the rDNA promoter.