The Beta-globin co-transcriptional cleavage ribozyme (CotC ribozyme) was proposed to be an RNAenzyme known as a ribozyme.
Transcription termination of RNA polymerase II transcripts is proposed to occur by a two-stage process. The first stage involves pre-termination cleavage (PTC) of the nascent transcript downstream of the poly(A) site. This process is also referred to as co-transcriptional cleavage (CoTC). The CoTC process in the human beta-globin gene was proposed to involve an RNA self-cleaving activity located in the 3' flanking region of the beta-globin gene. The CoTC core is highly conserved in the 3' UTR of other primate beta-globin genes.
However, there has been no independent confirmation of these findings, and a subsequent analysis by a team including members of the original report failed to demonstrate ribozyme activity.
^Teixeira A, Tahiri-Alaoui A, West S, Thomas B, Ramadass A, Martianov I, Dye M, James W, Proudfoot NJ, Akoulitchev A (2004). "Autocatalytic RNA cleavage in the human beta-globin pre-mRNA promotestranscription termination.". Nature. 432 (7016): 526–530. doi:10.1038/nature03032. PMID15565159.