FIGURE 3.
In some archaea, circular RNA is formed as an intermediate in ribosomal RNA processing. Ribosomal RNA precursors containing the bulge–helix–bulge motif are cleaved and ligated, forming circular intermediates which are further processed to release the 16S and 23S rRNA. rRNA regions are indicated by light blue; upstream and downstream regions contained within the circular intermediate are yellow and green, respectively.