Retrozymes are a unique class of non-LTR retroelements. These entities consist of a single, non-coding, genomic segment, carrying a catalytic RNA motifs, mainly self cleaving hammerhead ribozymes (HHRs). Some studies suggest retrozymes are mobilized through circular (circRNA) intermediates. Retrozymes are often found in plants and animals cells, though their exact distribution is likely to cover diverse, highly divergent eukaryotic lineages. While these entities share common structural similarities with other circular RNA entities (such as viroids and viroid-like agents), it remains unclear whether retrozymes (along with deltaviruses) share a common ancestor with other circRNAs.
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