Tag:Rz(N79) is a ribozyme cassette consisting of the N79 ribozyme flanked by A-rich spacer sequences (to ensure proper ribozyme folding). The N79 ribozyme is a modified version of a naturally occurring hammerhead ribozyme from Schistosoma mansoni that shows highly efficient and rapid-acting self-cleavage activity. This property can be used to knock down RNA expression; if Tag:Rz(N79) is inserted into an RNA of interest, self-cleavage by the N79 ribozyme can efficiently cleave the RNA, and the resulting fragments may be degraded (PMID:15386015).