The mammalian CPEB3 ribozyme is a self cleaving non-coding RNA

Non-coding RNA

A non-coding RNA is a functional RNA molecule that is not translated into a protein. Less-frequently used synonyms are non-protein-coding RNA , non-messenger RNA and functional RNA . The term small RNA is often used for short bacterial ncRNAs...

 located in the second intron

Intron

An intron is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. The term intron refers to both the DNA sequence within a gene, and the corresponding sequence in RNA transcripts. Sequences that are joined together in the final...

 of the CPEB3

CPEB

CPEB, or cytoplasmic polyadenylation element binding protein, is a highly conserved RNA-binding protein that promotes the elongation of the polyadenine tail of messenger RNA. CPEB most commonly activates the target RNA for translation, but can also act as a repressor, dependent on its...

 gene which belongs to a family of genes regulating messenger RNA polyadenylation

Polyadenylation

Polyadenylation is the addition of a poly tail to an RNA molecule. The poly tail consists of multiple adenosine monophosphates; in other words, it is a stretch of RNA that has only adenine bases. In eukaryotes, polyadenylation is part of the process that produces mature messenger RNA for translation...

. This ribozyme is highly conserved and
found only in mammals. The CPEB3 ribozyme is structurally and biochemically related to the human hepatitis delta virus ribozyme

Hepatitis delta virus ribozyme

The hepatitis delta virus ribozyme is a non-coding RNA that is necessary for viral replication and is thought to be the only catalytic RNA known to be required for viability of a human pathogen. The ribozyme acts to process the RNA transcripts to unit lengths in a self-cleavage reaction...

. Other HDV-like ribozymes have been identified and confirmed to be active in vitro in a number of eukaryotes.