Human XRN2 is involved in the torpedo model of transcription termination.
The C. elegans homologue, XRN-2, is involved in the degradation of certain mature miRNAs and their dislodging from miRISC miRNAs.
In yeast, the Rat1 protein has been shown to also be involved in the torpedo transcription termination model. When a polyadenylation site has been detected on the nascent RNA and cleaved by the RNA polymerase II, the Rtt103 factor recruits Rat1 and attaches it to free end. The exonuclease activity of Rat1 degrades the RNA strand and halts transcriptions upon catching up to the polymerase.
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